drm/amd/display: HP Reverb G2 VR fails to light up

[Why]
Many VR headsets require a HSYNC width of 4, but DCN
has default minimum of 8.

[How]
Change the arbitrary minimum HSYNC width to 4 to match
DCN20.
Signed-off-by: Aric Cyr <aric.cyr@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dce120/dce120_timing_generator.c

@@ -1268,7 +1268,7 @@ void dce120_timing_generator_construct(
 	tg110->min_h_front_porch = 0;
 	tg110->min_h_back_porch = 0;
 
-	tg110->min_h_sync_width = 8;
+	tg110->min_h_sync_width = 4;
 	tg110->min_v_sync_width = 1;
 	tg110->min_v_blank = 3;
 }

drivers/gpu/drm/amd/display/dc/dcn10/dcn10_optc.c

@@ -1540,7 +1540,7 @@ void dcn10_timing_generator_init(struct optc *optc1)
 	optc1->min_h_blank = 32;
 	optc1->min_v_blank = 3;
 	optc1->min_v_blank_interlace = 5;
-	optc1->min_h_sync_width = 8;
+	optc1->min_h_sync_width = 4;
 	optc1->min_v_sync_width = 1;
 }
 

drivers/gpu/drm/amd/display/dc/dcn30/dcn30_optc.c

@@ -350,7 +350,7 @@ void dcn30_timing_generator_init(struct optc *optc1)
 	optc1->min_h_blank = 32;
 	optc1->min_v_blank = 3;
 	optc1->min_v_blank_interlace = 5;
-	optc1->min_h_sync_width = 8;
+	optc1->min_h_sync_width = 4;
 	optc1->min_v_sync_width = 1;
 }