RDMA/rtrs-srv: Use per-cpu variables for rdma stats

Convert server stat counters from atomic to per-cpu variables.

Link: https://lore.kernel.org/r/20220712103113.617754-4-haris.iqbal@ionos.com


Signed-off-by: Santosh Kumar Pradhan <santosh.pradhan@ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>