RDMA/rxe: Fix rxe_modify_srq

RDMA/rxe: Fix rxe_modify_srq

This patch corrects an error in rxe_modify_srq where if the
caller changes the srq size the actual new value is not returned
to the caller since it may be larger than what is requested.
Additionally it open codes the subroutine rcv_wqe_size() which
adds very little value, and makes some whitespace changes.

Fixes: 8700e3e7c485 ("Soft RoCE driver")
Link: https://lore.kernel.org/r/20230620140142.9452-1-rpearsonhpe@gmail.com
Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>