drm/amd/display: avoid printing ERROR for unknown CEA parse(v2)

For the unknown CEA parse case on DMUB-enabled ASICs, dmesg will
print an error message like below, this will be captured by
automation tools as it has the word like ERROR during boot up
and treated as a false error, as it does not break bootup process.
So use DRM_WARN printing for this.

[drm:amdgpu_dm_update_freesync_caps [amdgpu]] *ERROR* Unknown EDID CEA parser results

v2: Use DRM_WARN to print such info.
Signed-off-by: Guchun Chen <guchun.chen@amd.com>
Reviewed-by: Stylon Wang <stylon.wang@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -10599,7 +10599,7 @@ static bool dm_edid_parser_send_cea(struct amdgpu_display_manager *dm,
 		vsdb->min_refresh_rate_hz = output->amd_vsdb.min_frame_rate;
 		vsdb->max_refresh_rate_hz = output->amd_vsdb.max_frame_rate;
 	} else {
-		DRM_ERROR("Unknown EDID CEA parser results\n");
+		DRM_WARN("Unknown EDID CEA parser results\n");
 		return false;
 	}