drm/radeon: remove overzealous warning in hdmi handling

hdmi audio works fine.  The warning just confuses users.

fixes:
https://bugzilla.kernel.org/show_bug.cgi?id=44341

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Cc: stable@vger.kernel.org

drivers/gpu/drm/radeon/r600_hdmi.c

@@ -544,7 +544,6 @@ void r600_hdmi_disable(struct drm_encoder *encoder)
 
 	/* Called for ATOM_ENCODER_MODE_HDMI only */
 	if (!dig || !dig->afmt) {
-		WARN_ON(1);
 		return;
 	}
 	if (!dig->afmt->enabled)