Kconfig: Add SPI / SPI_FLASH as dependencies

In order to use CMD_SF / CMD_SPI / ENV_IS_IN_SPI_FLASH we need to have
the SPI (or SPI_FLASH/DM_SPI_FLASH, for CMD_SF) enabled.  Express this
in the Kconfigs.

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
diff --git a/arch/Kconfig b/arch/Kconfig
index e574b0d..28afe39 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -101,6 +101,7 @@
 	imply CMD_IOTRACE
 	imply CMD_LZMADEC
 	imply CMD_SATA
+	imply CMD_SF
 	imply CMD_SF_TEST
 	imply CRC32_VERIFY
 	imply FAT_WRITE
@@ -147,6 +148,7 @@
 	imply CMD_IO
 	imply CMD_IRQ
 	imply CMD_PCI
+	imply CMD_SF
 	imply CMD_SF_TEST
 	imply CMD_ZBOOT
 	imply DM_ETH