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/at91sam9n12ek_mmc_defconfig b/configs/at91sam9n12ek_mmc_defconfig
index e61f3b9..3eb8666 100644
--- a/configs/at91sam9n12ek_mmc_defconfig
+++ b/configs/at91sam9n12ek_mmc_defconfig
@@ -18,4 +18,6 @@
 CONFIG_CMD_FAT=y
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_ATMEL=y
+CONFIG_USB=y
+CONFIG_USB_STORAGE=y
 CONFIG_OF_LIBFDT=y