drm/i915/display: clean up some gem/ includes

drm/i915/display: clean up some gem/ includes

Drop some unnecessary gem/ includes.

We seem to include xe_device.h through some compat gem headers, so we
need to include it directly in compat i915_drv.h to get
xe_device_has_flat_ccs().

Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/afd2917cc0a943660886937bb5f45c277132e147.1726589119.git.jani.nikula@intel.com