LU-13340 mgs: convert class_parse_nid4 to class_parse_nid

LU-13340 mgs: convert class_parse_nid4 to class_parse_nid

All callers of class_parse_nid4() now use class_parse_nid()
and so much handle a large nid.

do_lcfg_nid() is introduced to help with this.

Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: I502fa16871d689a8248e4243679918d58464efcd
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50094
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>