CACHE_REQ: Simplify _search_ncache_filter()
Let's make the result and input/output argument for
_search_ncache_filter() and free it inside the function whenever it's
needed instead of leaving this responsibility for the caller.
Related:
https://pagure.io/SSSD/sssd/issue/3362
Signed-off-by: Fabiano Fidêncio <fidencio@redhat.com>
Reviewed-by: Pavel Březina <pbrezina@redhat.com>