drm/xe/display: Silence kernel-doc warnings related to display

drm/xe/display: Silence kernel-doc warnings related to display

Add a "private:" comment to the part of the struct that is not expected
to be documented, the one with display-related fields. This silence the
following warnings:

	$ find drivers/gpu/drm/xe -name '*.[ch]' -not -path 'drivers/gpu/drm/xe/display/*'  |  xargs ./scripts/kernel-doc -Werror  -none
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'display' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'pch_type' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'pch_id' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'wm_lv_0_adjust_needed' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'num_channels' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'symmetric_memory' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'type' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'num_qgv_points' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'num_psf_gv_points' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'dram_info' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'runtime_pm' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'sb_lock' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'skl_preferred_vco_freq' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'max_dotclk_freq' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'hti_state' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'snps_phy_failed_calibration' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'modeset_restore_state' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'global_obj_list' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'de_irq_mask' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'display_irqs_enabled' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'enabled_irq_mask' not described in 'xe_device'
	drivers/gpu/drm/xe/xe_device_types.h:316: warning: Function parameter or member 'params' not described in 'xe_device'
	22 warnings as Errors

Fixes: 44e694958b95 ("drm/xe/display: Implement display support")
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Link: https://lore.kernel.org/r/20230315004902.2622613-1-lucas.demarchi@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>