[SCSI] cxgb3i: Fix error path for module init

If cxgb3i_pdu_init() fails, then it appears that cxgb3i_iscsi_init()
will not be cleaned up, leading to the iscsi transport being left
registered.  Fix this by adding a call to cxgb3i_iscsi_cleanup() on the
error path.

Signed-off-by: Roland Dreier <rolandd@cisco.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Cc: Karen Xie <kxie@chelsio.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>