RDMA/rtrs: Remove 'dir' argument from rnbd_srv_rdma_ev

Since process_{read,write} already prints direction info if ctx->ops.rdma_ev
fails, no need to pass 'dir'.

Link: https://lore.kernel.org/r/20220826081117.21687-1-guoqing.jiang@linux.dev


Signed-off-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Signed-off-by: Leon Romanovsky <leon@kernel.org>