[][openwrt][mt7988][eth][Add dynamic RSS support for Jaguar]

Add dynamic RSS support for Jaguar, which is quite
necessary for software path performance tuning.

In the previous commit (id: 7514813), we loosen the limitaions
of FE interrupt number, and then extend Rx path into
4-RSS rings. That commit makes it possible to dynamically
switch among 2/3/4-RSS rings by simply modifying indirection
table. So we add new proc interface for controlling
the number of RSS Rx rings.

- Show how many RSS Rx rings we're using now:
	$ cat /proc/mtketh/rss_ctrl

- Chang the number of RSS Rx rings (options: 2~4):
	$ echo [num] > /proc/mtketh/rss_ctrl

If without this patch, it's unable to dynamically
control RSS Rx rings.


Change-Id: Id5a8c91dcc7c5560d31eb9083e497b89ca35fa03
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/7561271
4 files changed