[SCSI] bnx2fc: Avoid calling bnx2fc_if_destroy with unnecessary locks

It is not required to hold rtnl_lock and bnx2fc_dev_lock when calling
bnx2fc_if_destroy, as the locking is only required to serialize creation and
deletion of fcoe instances. More importantly, this unnecessary locking causes
deadlock as bnx2fc_if_destroy calls fc_remove_host holding rtnl_lock.

Signed-off-by: Bhanu Prakash Gollapudi <bprakash@broadcom.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>