drm/dp: Add refresh rate divider to struct representing AS SDP

Add target_rr_divider to structure representing AS SDP.
It is valid only in FAVT mode, sink device ignores the bit in AVT
mode.

--v2:
- Update commit header and send patch to dri-devel.

Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240610072203.24956-6-mitulkumar.ajitkumar.golani@intel.com

include/drm/display/drm_dp_helper.h

@@ -122,6 +122,7 @@ struct drm_dp_as_sdp {
 	int target_rr;
 	int duration_incr_ms;
 	int duration_decr_ms;
+	bool target_rr_divider;
 	enum operation_mode mode;
 };