drm/amd/display: Enable 3 plane for DCN 3.01

Steam Deck/Gamescope wants to take advantage of more planes which is
possible on VanGogh but was not previously exposed.

Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Melissa Wen <mwen@igalia.com>
Cc: Simon Ser <contact@emersion.fr>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Joshua Ashton <joshua@froggi.es>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn301/dcn301_resource.c

@@ -1425,9 +1425,9 @@ static bool dcn301_resource_construct(
 	dc->caps.max_cursor_size = 256;
 	dc->caps.min_horizontal_blanking_period = 80;
 	dc->caps.dmdata_alloc_size = 2048;
-	dc->caps.max_slave_planes = 1;
-	dc->caps.max_slave_yuv_planes = 1;
-	dc->caps.max_slave_rgb_planes = 1;
+	dc->caps.max_slave_planes = 2;
+	dc->caps.max_slave_yuv_planes = 2;
+	dc->caps.max_slave_rgb_planes = 2;
 	dc->caps.is_apu = true;
 	dc->caps.post_blend_color_processing = true;
 	dc->caps.force_dp_tps4_for_cp2520 = true;