IB/core: Free GID table entry during GID deletion

If we already hold the table->lock when doing the kref_put it means we are
in a context where it is safe to do the deletion synchronously, with no
need for the work queue.

This helps to eliminate issues when GID change is requested as part of MAC
address change or bonding event change where expectation is to replace the
GID almost immediately.

Fixes: b150c386 ("IB/core: Introduce GID entry reference counts")
Reviewed-by: Daniel Jurgens <danielj@mellanox.com>
Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>