drm/radeon: make rv770_set_sw_state failures non-fatal

On some cards it takes a relatively long time for the change
to take place.  Make a timeout non-fatal.

bug:
https://bugs.freedesktop.org/show_bug.cgi?id=76130

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

drivers/gpu/drm/radeon/rv770_dpm.c

@@ -1418,7 +1418,7 @@ int rv770_resume_smc(struct radeon_device *rdev)
 int rv770_set_sw_state(struct radeon_device *rdev)
 {
 	if (rv770_send_msg_to_smc(rdev, PPSMC_MSG_SwitchToSwState) != PPSMC_Result_OK)
-		return -EINVAL;
+		DRM_ERROR("rv770_set_sw_state failed\n");
 	return 0;
 }