uek-rpm: optimize find-requires usage

uek-rpm: optimize find-requires usage

There are no deps found for debuginfo-common, doc and headers subpackage, so
Autoreq: no is now set for them, also switch from /usr/lib/rpm/redhat/find-requires
usage to /usr/lib/rpm/rpmdeps --requires, since latter is faster and less buggy.
Both changes noticeably boost kernel rpm build time.

Orabug: 29323635

Signed-off-by: Alex Burmashev <alexander.burmashev@oracle.com>
Reviewed-by: Somasundaram Krishnasamy <somasundaram.krishnasamy@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>