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/cmd/Kconfig b/cmd/Kconfig
index 0badcb3..cda7931 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1035,11 +1035,13 @@
 
 config CMD_SF
 	bool "sf"
+	depends on DM_SPI_FLASH || SPI_FLASH
 	help
 	  SPI Flash support
 
 config CMD_SF_TEST
 	bool "sf test - Allow testing of SPI flash"
+	depends on CMD_SF
 	help
 	  Provides a way to test that SPI flash is working correctly. The
 	  test is destructive, in that an area of SPI flash must be provided
@@ -1051,6 +1053,7 @@
 
 config CMD_SPI
 	bool "sspi - Command to access spi device"
+	depends on SPI
 	help
 	  SPI utility command.