CLEANUP: acl: remove duplicate test in parse_acl_expr() and unused variable

CLEANUP: acl: remove duplicate test in parse_acl_expr() and unused variable

aclkw->match_type was compared twice to PAT_MATCH_DOM in parse_acl_expr().
After auditing the involved types, it's only a copy-paste mistake, as no
other matching method is missing, so let's drop it to avoid the confusion.
Also drop variable ckw which is assigned NULL and passed to free(), and is
clearly a leftover from a previous version.

No backport needed.