RDMA/rvt: Fix potential memory leak caused by rvt_alloc_rq

In case of failure of alloc_ud_wq_attr(), the memory allocated by
rvt_alloc_rq() is not freed. Fix it by calling rvt_free_rq() using the
existing clean-up code.

Fixes: d310c4bf

 ("IB/{rdmavt, hfi1, qib}: Remove AH refcount for UD QPs")
Link: https://lore.kernel.org/r/20200614041148.131983-1-pakki001@umn.edu
Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Acked-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>