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/corvus_defconfig b/configs/corvus_defconfig
index a3f144d..2f3803a 100644
--- a/configs/corvus_defconfig
+++ b/configs/corvus_defconfig
@@ -67,7 +67,7 @@
 CONFIG_SYS_NAND_OOBSIZE=0x40
 CONFIG_SYS_NAND_U_BOOT_LOCATIONS=y
 CONFIG_SYS_NAND_U_BOOT_OFFS=0x20000
-CONFIG_PHYLIB=y
+CONFIG_MACB=y
 CONFIG_ATMEL_USART=y
 CONFIG_USB=y
 CONFIG_USB_EHCI_HCD=y