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/ethernut5_defconfig b/configs/ethernut5_defconfig
index 0faeb63..1cf38b8 100644
--- a/configs/ethernut5_defconfig
+++ b/configs/ethernut5_defconfig
@@ -34,6 +34,7 @@
 CONFIG_CMD_DHCP=y
 CONFIG_CMD_RARP=y
 CONFIG_CMD_MII=y
+# CONFIG_CMD_MDIO is not set
 CONFIG_CMD_PING=y
 CONFIG_CMD_CDP=y
 CONFIG_CMD_SNTP=y
@@ -69,6 +70,7 @@
 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_RTC_PCF8563=y