drm/amd/display: fix ref count leak in amdgpu_drm_ioctl

in amdgpu_drm_ioctl the call to pm_runtime_get_sync increments the
counter even in case of failure, leading to incorrect
ref count. In case of failure, decrement the ref count before returning.

Signed-off-by: Navid Emamdoost <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c

···
 	dev = file_priv->minor->dev;
 	ret = pm_runtime_get_sync(dev->dev);
 	if (ret < 0)
-		return ret;
+		goto out;
 
 	ret = drm_ioctl(filp, cmd, arg);
 
 	pm_runtime_mark_last_busy(dev->dev);
+out:
 	pm_runtime_put_autosuspend(dev->dev);
 	return ret;
 }