be2iscsi: Added return value check for mgmt_get_all_if_id

Use of mutex_lock_interruptible can return -EINTR, handle and log the
error.

Signed-off-by: Jitendra Bhivare <jitendra.bhivare@avagotech.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>