configs: Make NAND_BOOT and ONENAND_BOOT imply NAND

Some boards indicate support from booting NAND or
ONENAND booting, but don't enable the CONFIG_NAND.  This
makes those boards imply NAND which will make
enabling other flags that are dependent on CONFIG_NAND
possible and easier to migrate.

Signed-off-by: Adam Ford <aford173@gmail.com>
diff --git a/common/Kconfig b/common/Kconfig
index 81e88ea..dc2e1c2 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -125,6 +125,7 @@
 config NAND_BOOT
 	bool "Support for booting from NAND flash"
 	default n
+	imply NAND
 	help
 	  Enabling this will make a U-Boot binary that is capable of being
 	  booted via NAND flash. This is not a must, some SoCs need this,
@@ -133,6 +134,7 @@
 config ONENAND_BOOT
 	bool "Support for booting from ONENAND"
 	default n
+	imply NAND
 	help
 	  Enabling this will make a U-Boot binary that is capable of being
 	  booted via ONENAND. This is not a must, some SoCs need this,