spi: add driver for MTK SPI NAND Flash Interface

This driver implements support for the SPI-NAND mode of MTK NAND Flash
Interface as a SPI-MEM controller with pipelined ECC capability.

Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
Tested-by: Daniel Golle <daniel@makrotopia.org>
Link: https://lore.kernel.org/r/20220424032527.673605-3-gch981213@gmail.com


Signed-off-by: Mark Brown <broonie@kernel.org>