RDMA/rxe: Fix a typo in opcode name

There is a redundant ']' in the name of opcode IB_OPCODE_RC_SEND_MIDDLE,
so just fix it.

Fixes: 8700e3e7

 ("Soft RoCE driver")
Link: https://lore.kernel.org/r/20211218112320.3558770-1-cgxu519@mykernel.net
Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>
Acked-by: Zhu Yanjun <zyjzyj2000@gmail.com>
Reviewed-by: Bob Pearson <rpearsonhpe@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>