drm/dp: Add argument for max luminance in drm_edp_backlight_init

drm/dp: Add argument for max luminance in drm_edp_backlight_init

Add new argument to drm_edp_backlight_init which gives the
max_luminance which will be needed to set the max values for
backlight.

--v2
-Use pass only max luminance instead of luminance_range_info struct
[Arun]

Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Link: https://lore.kernel.org/r/20250620063445.3603086-4-suraj.kandpal@intel.com