IB/hfi1: Move receive work queue struct into uapi directory

The rvt_rwqe and rvt_rwq struct elements are shared between rdmavt and the
providers but are not in uapi directory.  As per the comment in
https://marc.info/?l=linux-rdma&m=152296522708522&w=2, The hfi1 driver and
the rdma core driver are not using shared structures in the uapi
directory.

Move rvt_rwqe and rvt_rwq struct into rvt-abi.h header in uapi directory.

Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Signed-off-by: Kamenee Arumugam <kamenee.arumugam@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>