drm/vmwgfx: prevent memory leak in vmw_cmdbuf_res_add

In vmw_cmdbuf_res_add if drm_ht_insert_item fails the allocated memory
for cres should be released.

Fixes: 18e4a4669c50 ("drm/vmwgfx: Fix compat shader namespace")
Signed-off-by: Navid Emamdoost <[e-mail]>
Reviewed-by: Thomas Hellstrom <[e-mail]>
Signed-off-by: Thomas Hellstrom <[e-mail]>

drivers/gpu/drm/vmwgfx/vmwgfx_cmdbuf_res.c

···
 
 	cres->hash.key = user_key | (res_type << 24);
 	ret = drm_ht_insert_item(&man->resources, &cres->hash);
-	if (unlikely(ret != 0))
+	if (unlikely(ret != 0)) {
+		kfree(cres);
 		goto out_invalid_key;
+	}
 
 	cres->state = VMW_CMDBUF_RES_ADD;
 	cres->res = vmw_resource_reference(res);