configs: Migrate CONFIG_USB_STORAGE

In some cases we were missing CONFIG_USB=y so enable that when needed.

Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/digsy_mtc_defconfig b/configs/digsy_mtc_defconfig
index 977d3b2..e2156a1 100644
--- a/configs/digsy_mtc_defconfig
+++ b/configs/digsy_mtc_defconfig
@@ -18,4 +18,6 @@
 CONFIG_CMD_CACHE=y
 CONFIG_CMD_EXT2=y
 CONFIG_CMD_FAT=y
+CONFIG_USB=y
+CONFIG_USB_STORAGE=y
 CONFIG_OF_LIBFDT=y