RDMA/rtrs: Remove all likely and unlikely

The IO performance test with fio after swapping the likely and unlikely
macros in all if-statement shows no difference.  They do not help for the
performance of rtrs.

Thanks to Haakon Bugge for the test scenario.

The fio test did random read on 32 rnbd devices and 64 processes.
Test environment:
- Intel(R) Xeon(R) Gold 6130 CPU @ 2.10GHz
- 376G memory
- kernel version: 5.4.86
- gcc version: gcc (Debian 8.3.0-6) 8.3.0
- Infiniband controller: Mellanox Technologies MT27800 Family [ConnectX-5]

Test result:
- before swapping:       IOPS=829k, BW=3239MiB/s
- after swapping:        IOPS=829k, BW=3238MiB/s
- remove all (un)likely: IOPS=829k, BW=3238MiB/s

Link: https://lore.kernel.org/r/20210806112112.124313-5-haris.iqbal@ionos.com


Signed-off-by: Gioh Kim <gi-oh.kim@ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>