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/snapper9260_defconfig b/configs/snapper9260_defconfig
index 4a2527c..4b3267e 100644
--- a/configs/snapper9260_defconfig
+++ b/configs/snapper9260_defconfig
@@ -28,6 +28,7 @@
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_CMD_DHCP=y
 CONFIG_CMD_MII=y
+# CONFIG_CMD_MDIO is not set
 CONFIG_CMD_PING=y
 CONFIG_CMD_FAT=y
 CONFIG_ENV_OVERWRITE=y
@@ -44,4 +45,5 @@
 CONFIG_MTD_RAW_NAND=y
 # CONFIG_SYS_NAND_USE_FLASH_BBT is not set
 CONFIG_NAND_ATMEL=y
+CONFIG_MACB=y
 CONFIG_ATMEL_USART=y