IB/core: Eliminate sparse false context imbalance warning

When write_gid function needs to do a sleep-able operation, it unlocks
table->rwlock and then relocks it. Sparse complains about context
imbalance.

This is safe as write_gid is always called with table->rwlock.
write_gid protects from simultaneous writes to this GID entry
by setting the GID_TABLE_ENTRY_INVALID flag.

Fixes: 9c584f049596 ('IB/core: Change per-entry lock in RoCE GID table to
		     one lock')
Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/core/cache.c

@@ -174,6 +174,7 @@ static int write_gid(struct ib_device *ib_dev, u8 port,
 		     const struct ib_gid_attr *attr,
 		     enum gid_table_write_action action,
 		     bool  default_gid)
+	__releases(&table->rwlock) __acquires(&table->rwlock)
 {
 	int ret = 0;
 	struct net_device *old_net_dev;