mtd: nand: Add Mediatek machine dependency

The Mediatek NAND driver is only needed for a specific
platform, so avoid cluttering the configuration.
Signed-off-by: NEzequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: NBoris Brezillon <boris.brezillon@free-electrons.com>

drivers/mtd/nand/Kconfig

@@ -556,6 +556,7 @@ config MTD_NAND_QCOM
 
 config MTD_NAND_MTK
 	tristate "Support for NAND controller on MTK SoCs"
+	depends on ARCH_MEDIATEK || COMPILE_TEST
 	depends on HAS_DMA
 	help
 	  Enables support for NAND controller on MTK SoCs.