[][openwrt][mt7988][pce][support get CDRT index API]

[Description]
Add CDRT acquire API.
CDRT structure is embedded with CLS entry to indicate CDRT related CLS
entry.
Some of kernel modules, such as TOPS, require to check CDRT is exist or
not to decide how to fill up CLS descritor. If CLS is already filled up
with crypto related information, other kernel modules should not modify
the packet pattern rule. Instead, they can only update the tport or some
of CLS actions.

[Release-log]
N/A

Change-Id: If1e2827d354d414ef2f046864ff3c46af863fe4e
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/7923906
2 files changed