drm/amd/display: update max streams per surface

Increse to 6 as that is the max surfaces supported asics can have.
The is no practical use case yet, but this is valuable for pre-si
validation.
Reviewed-by: Ariel Bernstein <Eric.Bernstein@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dc_types.h

@@ -83,7 +83,7 @@ struct dc_perf_trace {
 	unsigned long last_entry_write;
 };
 
-#define MAX_SURFACE_NUM 4
+#define MAX_SURFACE_NUM 6
 #define NUM_PIXEL_FORMATS 10
 
 enum tiling_mode {