drm/amd/powerplay: fix a couple locking issues

We should return unlock on the error path in pp_dpm_dispatch_tasks()
and there is a double lock bug in pp_dpm_set_sclk_od().

Fixes: 2a5071056e6a ("drm/amd/powerplay: add global PowerPlay mutex.")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/powerplay/amd_powerplay.c

@@ -493,8 +493,10 @@ static int pp_dpm_dispatch_tasks(void *handle, enum amd_pp_event event_id,
 	{
 		enum amd_pm_state_type  ps;
 
-		if (input == NULL)
-			return -EINVAL;
+		if (input == NULL) {
+			ret = -EINVAL;
+			break;
+		}
 		ps = *(unsigned long *)input;
 
 		data.requested_ui_label = power_state_convert(ps);