nvmet-tcp: remove has_keyed_sgls initialization

Since the nvmet_tcp_ops is static, there is no need to initialize values
to zero.

Signed-off-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Israel Rukshin <israelr@mellanox.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>