cmd: nand: Make the NAND options default to NAND_SUNXI

If we depend on the ARCH_SUNXI configuration option, the boards that do not
have NAND support enabled (with the associated options) will not compile
anymore.

Depend on the NAND driver configuration option to make sure that is not the
case.
Reported-by: NChen-Yu Tsai <wens@csie.org>
Tested-by: NChen-Yu Tsai <wens@csie.org>
Reviewed-by: NAndre Przywara <andre.przywara@arm.com>
Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>

cmd/Kconfig

@@ -452,7 +452,7 @@ config CMD_MMC
 
 config CMD_NAND
 	bool "nand"
-	default y if ARCH_SUNXI
+	default y if NAND_SUNXI
 	help
 	  NAND support.
 
@@ -847,7 +847,7 @@ config CMD_UBI
 	tristate "Enable UBI - Unsorted block images commands"
 	select CRC32
 	select MTD_UBI
-	default y if ARCH_SUNXI
+	default y if NAND_SUNXI
 	help
 	  UBI is a software layer above MTD layer which admits use of LVM-like
 	  logical volumes on top of MTD devices, hides some complexities of
@@ -862,7 +862,7 @@ config CMD_UBIFS
 	select CRC32
 	select RBTREE if ARCH_SUNXI
 	select LZO if ARCH_SUNXI
-	default y if ARCH_SUNXI
+	default y if NAND_SUNXI
 	help
 	  UBIFS is a file system for flash devices which works on top of UBI.