drm: add PSR2 support and capability definition as per eDP 1.5

[why & how]
As per eDP 1.5 spec, add the below two DPCD bit fields for PSR-SU
support and capability:

1. DP_PSR2_WITH_Y_COORD_ET_SUPPORTED
2. DP_PSR2_SU_AUX_FRAME_SYNC_NOT_NEEDED

changes in v2
------------------
* fixed the typo
* explicitly list what DPCD bit fields are added

Signed-off-by: David Zhang <dingchen.zhang@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

include/drm/dp/drm_dp_helper.h

@@ -361,6 +361,7 @@ struct drm_panel;
 # define DP_PSR_IS_SUPPORTED                1
 # define DP_PSR2_IS_SUPPORTED		    2	    /* eDP 1.4 */
 # define DP_PSR2_WITH_Y_COORD_IS_SUPPORTED  3	    /* eDP 1.4a */
+# define DP_PSR2_WITH_Y_COORD_ET_SUPPORTED  4	    /* eDP 1.5, adopted eDP 1.4b SCR */
 
 #define DP_PSR_CAPS                         0x071   /* XXX 1.2? */
 # define DP_PSR_NO_TRAIN_ON_EXIT            1
@@ -375,6 +376,7 @@ struct drm_panel;
 # define DP_PSR_SETUP_TIME_SHIFT            1
 # define DP_PSR2_SU_Y_COORDINATE_REQUIRED   (1 << 4)  /* eDP 1.4a */
 # define DP_PSR2_SU_GRANULARITY_REQUIRED    (1 << 5)  /* eDP 1.4b */
+# define DP_PSR2_SU_AUX_FRAME_SYNC_NOT_NEEDED (1 << 6)/* eDP 1.5, adopted eDP 1.4b SCR */
 
 #define DP_PSR2_SU_X_GRANULARITY	    0x072 /* eDP 1.4b */
 #define DP_PSR2_SU_Y_GRANULARITY	    0x074 /* eDP 1.4b */