dlm: use hlist_for_each_entry_srcu for SRCU protected lists

dlm: use hlist_for_each_entry_srcu for SRCU protected lists

The connection and node hash tables in DLM are protected by SRCU, but
the code currently uses hlist_for_each_entry_rcu() for traversal.
While this works functionally, it is semantically incorrect and triggers
warnings when RCU lockdep debugging is enabled, as it expects regular
RCU read-side critical sections.

This patch replaces the incorrect macros with hlist_for_each_entry_srcu()
and adds the appropriate lockdep expressions using srcu_read_lock_held()
to ensure consistency with the underlying locking mechanism.

Signed-off-by: Li RongQing <lirongqing@baidu.com>
Acked-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>