Convert CONFIG_MACB to Kconfig

This converts the following to Kconfig:
   CONFIG_MACB

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/usb_a9263_dataflash_defconfig b/configs/usb_a9263_dataflash_defconfig
index 5bf0e75..f138514 100644
--- a/configs/usb_a9263_dataflash_defconfig
+++ b/configs/usb_a9263_dataflash_defconfig
@@ -47,6 +47,7 @@
 CONFIG_DM_SPI_FLASH=y
 CONFIG_SPI_FLASH_ATMEL=y
 CONFIG_SPI_FLASH_DATAFLASH=y
+CONFIG_MACB=y
 CONFIG_PINCTRL=y
 CONFIG_PINCTRL_AT91=y
 CONFIG_DM_SERIAL=y