RDMA/cxgb4: Don't re-init wait object in init/fini paths

Re-initializing the wait object in rdma_init()/rdma_fini() causes a
timing window which can lead to a deadlock during close.  Once this
deadlock hits, all RDMA activity over the T4 device will be stuck.

There's no need to re-init the wait object, so remove it.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Cc: <stable@kernel.org>
Signed-off-by: Roland Dreier <rolandd@cisco.com>