nand: raw: add support for MediaTek MT7621 SoC

This patch adds NAND flash controller driver for MediaTek MT7621 SoC.
The NAND flash controller of MT7621 supports only SLC NAND flashes.
It supports 4~12 bits correction with maximum 4KB page size.

Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>
5 files changed