drm/amdgpu: Add missing pm_runtime_put_autosuspend

pm_runtime_get_sync() increments the runtime PM usage counter even
when it returns an error code, thus a matching decrement is needed
on the error handling path to keep the counter balanced.
Signed-off-by: Yongzhi Liu <lyz_cs@pku.edu.cn>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1120,8 +1120,10 @@ static ssize_t amdgpu_debugfs_gfxoff_read(struct file *f, char __user *buf,
 		return -EINVAL;
 
 	r = pm_runtime_get_sync(adev_to_drm(adev)->dev);
-	if (r < 0)
+	if (r < 0) {
+		pm_runtime_put_autosuspend(adev_to_drm(adev)->dev);
 		return r;
+	}
 
 	while (size) {
 		uint32_t value;