RDMA/mlx5: Fix compilation warning when USER_ACCESS isn't set

The cited commit made fs.c always compile, even when
INFINIBAND_USER_ACCESS isn't set. This results in a compilation
warning about an unused object when compiling with W=1 and
USER_ACCESS is unset.

Fix this by defining uverbs_destroy_def_handler() even when
USER_ACCESS isn't set.

Fixes: 36e0d433672f ("RDMA/mlx5: Compile fs.c regardless of INFINIBAND_USER_ACCESS config")
Link: https://patch.msgid.link/r/[e-mail]
Signed-off-by: Mark Bloch <[e-mail]>
Tested-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Jason Gunthorpe <[e-mail]>

drivers/infiniband/hw/mlx5/fs.c

···
 	&UVERBS_METHOD(MLX5_IB_METHOD_STEERING_ANCHOR_DESTROY));
 
 const struct uapi_definition mlx5_ib_flow_defs[] = {
-#if IS_ENABLED(CONFIG_INFINIBAND_USER_ACCESS)
 	UAPI_DEF_CHAIN_OBJ_TREE_NAMED(
 		MLX5_IB_OBJECT_FLOW_MATCHER),
 	UAPI_DEF_CHAIN_OBJ_TREE(
···
 	UAPI_DEF_CHAIN_OBJ_TREE_NAMED(
 		MLX5_IB_OBJECT_STEERING_ANCHOR,
 		UAPI_DEF_IS_OBJ_SUPPORTED(mlx5_ib_shared_ft_allowed)),
-#endif
 	{},
 };
 

include/rdma/ib_verbs.h

···
 
 struct ib_ucontext *ib_uverbs_get_ucontext_file(struct ib_uverbs_file *ufile);
 
+#if IS_ENABLED(CONFIG_INFINIBAND_USER_ACCESS)
 int uverbs_destroy_def_handler(struct uverbs_attr_bundle *attrs);
+#else
+static inline int uverbs_destroy_def_handler(struct uverbs_attr_bundle *attrs)
+{
+	return 0;
+}
+#endif
 
 struct net_device *rdma_alloc_netdev(struct ib_device *device, u32 port_num,
 				     enum rdma_netdev_t type, const char *name,