[][OpenWrt Dev][Enable NMBM for mt7986 spim-nand]

[Description]
Add NMBM support for mt7986 spim-nand

[Release-log]
N/A

Change-Id: If835ff6a9d6664e5abde618928290ae35edb6ed6
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/4672482
2 files changed