IPoIB: Fix leak in ipoib_transport_dev_init() error path

ipoib_transport_dev_init() calls ipoib_cm_dev_init(), so it needs to
call ipoib_cm_dev_cleanup() to unwind that on the error path.

Found by Dotan Barak of Mellanox.

Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>