drm/i915/backlight: Use proper interface based on eDP version

eDP is supposed to use VESA interface when using revision 1.5 and above,
use Intel interface for backlight control otherwise. Add check to
use correct interface.

Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Tested-by: Ben Kao <ben.kao@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250206063253.2827017-4-suraj.kandpal@intel.com