drm/i915: include uapi/drm/i915_drm.h directly where needed

Remove the uapi/drm/i915_drm.h include from drm/i915_drm.h, and stop
being a proxy for uapi/drm/i915_drm.h. Include uapi/drm/i915_drm.h and
drm/i915_drm.h only where needed.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220311100639.114685-2-jani.nikula@intel.com