[][mtd: mtk-snand: add tuning parameters for mt7622/mt7629/mt7986]

[Description]
Add tuning parameters to fit in each platform. In theory, these values perfectly match our reference board. But in some circumstances, like flash socket installed, you need to tune these values again. This patch allows you to do that.

[Release-log]
N/A

Change-Id: If4d997309abbad3193836b0f4d7a16cced901a20
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/4721474
2 files changed