RDMA/rxe: Remove the is_user members of struct rxe_sq/rxe_rq/rxe_srq

RDMA/rxe: Remove the is_user members of struct rxe_sq/rxe_rq/rxe_srq

BugLink: https://bugs.launchpad.net/bugs/1990162
[ Upstream commit 1cf2ce8272802e677398fab47a73713bc6e1fd5c ]

The is_user members of struct rxe_sq/rxe_rq/rxe_srq are unsed since
commit ae6e843fe08d ("RDMA/rxe: Add memory barriers to kernel queues").
In this case, it is fine to remove them directly.

Link: https://lore.kernel.org/r/20210930094813.226888-2-yangx.jy@fujitsu.com
Signed-off-by: Xiao Yang <yangx.jy@fujitsu.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>