drm/amd/display: Check if Mode is Supported Before Returning Result

[Why]
Even if the mode is not supported dml2_check_mode_supported() would still return true.
This causes an unsupported mode to be programmed.

[How]
Check if the mode is supported or not and return the proper result.
Reviewed-by: Chaitanya Dhere <chaitanya.dhere@amd.com>
Signed-off-by: Austin Zheng <austin.zheng@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dml2/dml21/src/dml2_top/dml_top.c

@@ -138,8 +138,9 @@ bool dml2_check_mode_supported(struct dml2_check_mode_supported_in_out *in_out)
 	}
 
 	in_out->is_supported = mcache_success;
+	result = result && in_out->is_supported;
 
-	return true;
+	return result;
 }
 
 bool dml2_build_mode_programming(struct dml2_build_mode_programming_in_out *in_out)