RDMA/siw: replace redundant ternary operator with just rv

RDMA/siw: replace redundant ternary operator with just rv

The use of the ternary operator on rv is redundant, rv is
either the initialized value of 0 or a negative error return
code, so it can never be greater than zero, and hence the
zero assignment in ternary operator is redundant. Just return
rv instead.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://patch.msgid.link/20250507131834.253823-1-colin.i.king@gmail.com
Acked-by: Bernard Metzler <bmt@zurich.ibm.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>