RDMA/rtrs-srv: Add event tracing support

Add event tracing mechanism for following routines:
- send_io_resp_imm()

How to use:
1. Load the rtrs_server module
2. cd /sys/kernel/debug/tracing
3. If all the events need to be enabled:
echo 1 > events/rtrs_srv/enable
4. OR only speific routine/event needs to be enabled e.g.
echo 1 > events/rtrs_srv/send_io_resp_imm/enable
5. cat trace
6. Run some I/O workload which can trigger send_io_resp_imm()

Link: https://lore.kernel.org/r/20220818105240.110234-3-haris.iqbal@ionos.com
Signed-off-by: Santosh 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>