LU-9859 llite: simplify parsing in pcc_conds_parse()

LU-9859 llite: simplify parsing in pcc_conds_parse()

If we duplicate the string to be parsed we can use standard parsing
tools like strsep() and strcmp().

Test-Parameters: trivial testlist=sanity-pcc
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: Ia0d0fb4fbc8d85f1e47e6085392e0f84b000b8a8
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50839
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Feng Lei <flei@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Qian Yingjin <qian@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>