Convert CONFIG_FSL_MEMAC et al to Kconfig

This converts the following to Kconfig:
   CONFIG_FSL_MEMAC
   CONFIG_SYS_MEMAC_LITTLE_ENDIAN

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/lx2162aqds_tfa_defconfig b/configs/lx2162aqds_tfa_defconfig
index 216ac80..68cdefb 100644
--- a/configs/lx2162aqds_tfa_defconfig
+++ b/configs/lx2162aqds_tfa_defconfig
@@ -92,6 +92,8 @@
 CONFIG_SYS_CORTINA_NO_FW_UPLOAD=y
 CONFIG_PHY_REALTEK=y
 CONFIG_PHY_VITESSE=y
+CONFIG_FSL_MEMAC=y
+CONFIG_SYS_MEMAC_LITTLE_ENDIAN=y
 CONFIG_DM_ETH=y
 CONFIG_DM_MDIO=y
 CONFIG_DM_MDIO_MUX=y