RDMA/cma: Fix hardware address comparison length in netevent callback

RDMA/cma: Fix hardware address comparison length in netevent callback

The cited commit hardcoded the hardware address comparison len to ETH_ALEN.

This breaks IPoIB, which uses 20-byte addresses. By truncating the
memcmp, the CMA may incorrectly assume the target address is
unchanged and fails to abort the stalled connection.

Fix this by replacing ETH_ALEN with the dynamic neigh->dev->addr_len
to correctly evaluate the full address regardless of the link layer.

Fixes: 925d046e7e52 ("RDMA/core: Add a netevent notifier to cma")
Signed-off-by: Or Gerlitz <ogerlitz@ddn.com>
Link: https://patch.msgid.link/20260617-fix-cma-ipoib-v1-1-03f869344304@ddn.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>