RDMA/siw: Remove siw_sk_save_upcalls

Let's move it into siw_sk_assign_cm_upcalls, then we only
need to get sk_callback_lock once.

Acked-by: Bernard Metzler <bmt@zurich.ibm.com>
Signed-off-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Link: https://lore.kernel.org/r/20231113115726.12762-14-guoqing.jiang@linux.dev


Signed-off-by: Leon Romanovsky <leon@kernel.org>