RDMA/core: Reduce cond_resched() frequency in __ib_umem_release

RDMA/core: Reduce cond_resched() frequency in __ib_umem_release

The current implementation calls cond_resched() for every SG entry
in __ib_umem_release(), which can increase needless overhead.

This patch introduces RESCHED_LOOP_CNT_THRESHOLD (0x1000) to limit
how often cond_resched() is called. The function now yields the CPU
once every 4096 iterations, and yield at the very first iteration
for lots of small umem case, to reduce scheduling overhead.

Fixes: d056bc45b62b ("RDMA/core: Prevent soft lockup during large user memory region cleanup")
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Link: https://patch.msgid.link/20251126025147.2627-1-lirongqing@baidu.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>