RDMA/rxe: support perf mgmt GET method

RDMA/rxe: support perf mgmt GET method

In RXE, hardware counters are already supported, but not in a
standardized manner. For instance, user-space monitoring tools like
atop only read from the *counters* directory. Therefore, it is
necessary to add perf management support to RXE.

Also use rxe_counter_get instead of raw atomic64_read in hw-counters.

Signed-off-by: zhenwei pi <zhenwei.pi@linux.dev>
Link: https://patch.msgid.link/20260414062948.671658-4-zhenwei.pi@linux.dev
Signed-off-by: Leon Romanovsky <leon@kernel.org>