microblaze: Enable axi emac via Kconfig

Enable driver by default for all platforms.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/configs/microblaze-generic_defconfig b/configs/microblaze-generic_defconfig
index 325c1bb..047ed17 100644
--- a/configs/microblaze-generic_defconfig
+++ b/configs/microblaze-generic_defconfig
@@ -11,6 +11,7 @@
 CONFIG_SPL_OF_CONTROL=y
 CONFIG_OF_EMBED=y
 CONFIG_DM_ETH=y
+CONFIG_XILINX_AXIEMAC=y
 CONFIG_XILINX_EMACLITE=y
 CONFIG_SYS_NS16550=y
 CONFIG_XILINX_UARTLITE=y