mediatek: enable new spi-nand driver for kernel 5.10

This patch enables new spi-nand driver for mt7622 and mt7629.

Signed-off-by: Weijie Gao <hackpascal@gmail.com>
Signed-off-by: Chuanhong Guo <gch981213@gmail.com>

target/linux/mediatek/mt7622/config-5.10

@@ -273,6 +273,7 @@ CONFIG_MTK_HSDMA=y
 CONFIG_MTK_INFRACFG=y
 CONFIG_MTK_PMIC_WRAP=y
 CONFIG_MTK_SCPSYS=y
+CONFIG_MTK_SPI_NAND=y
 CONFIG_MTK_THERMAL=y
 CONFIG_MTK_TIMER=y
 # CONFIG_MTK_UART_APDMA is not set