Add MediaTek MT7986 SPI NAND support

Merge series from Xiangsheng Hou <xiangsheng.hou@mediatek.com>:

This patch series split from bellow series which pick-up spi relevant patches
https://lore.kernel.org/all/20230130030656.12127-1-xiangsheng.hou@mediatek.com.
This series add MediaTek MT7986 SPI NAND controller support, add read latch
latency, smaple delay adjust and add optional nfi_hclk.