LU-10391 obd: Update lmd_parse to handle IPv6 NIDs

LU-10391 obd: Update lmd_parse to handle IPv6 NIDs

lmd_find_delimiter()/lmd_parse_nidlist() are updated to handle IPv6
NIDs.

class_parse_value() is updated to handle IPv6 NIDs that begin with
'::'. Also, when parsing a Lustre network name, the buffer needn't
contain an '@', nor do we want to search for '@' when locating the
next delimiter.

Fixes: 101f6e8 ("LU-10391 obdclass: handle large NIDs for mount strings")
Signed-off-by: Chris Horn <chris.horn@hpe.com>
Change-Id: Ib9e5a0d161babfea368989dd9521d923ec592185
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/53882
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: Oleg Drokin <green@whamcloud.com>