Commit f0626710 ("RDMA: Update workqueue usage") removed
content of qib_qsfp_deinit(...) and left it empty.

This patch deletes all leftovers of that function.
Signed-off-by: NLeon Romanovsky <leon@kernel.org>
Reviewed-by: NYuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>