staging: lustre: ldlm: use list_for_each_entry in ldlm_resource.c

Having a stand-alone "list_entry()" call is often a sign
that something like "list_for_each_entry()" would
make the code clearer.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>