RDMA/rtrs-srv: Refactor rtrs_srv_rdma_cm_handler

The RDMA_CM_EVENT_CONNECT_REQUEST is quite different to other types,
let's check it separately at the beginning of routine, then we can
avoid the indentation accordingly.

Acked-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Link: https://lore.kernel.org/r/20221117101945.6317-2-guoqing.jiang@linux.dev


Signed-off-by: Leon Romanovsky <leon@kernel.org>