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/silk_defconfig b/configs/silk_defconfig
index 604975d..a0259a7 100644
--- a/configs/silk_defconfig
+++ b/configs/silk_defconfig
@@ -25,3 +25,5 @@
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_BAR=y
 CONFIG_SPI_FLASH_SPANSION=y
+CONFIG_USB=y
+CONFIG_USB_STORAGE=y