x86: galileo: Enable random mac address for Quark

Not like other Intel Ethernet controllers (e.g.: E1000), Intel Quark
SoC integrated designware Ethernet controller does not have a chipset
defined way to store/restore mac address. Enable random mac address
so that we can use Ethernet even without 'ethaddr'.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>

configs/galileo_defconfig

@@ -11,6 +11,7 @@ CONFIG_BOOTSTAGE=y
 CONFIG_BOOTSTAGE_REPORT=y
 CONFIG_CMD_BOOTSTAGE=y
 CONFIG_OF_CONTROL=y
+CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_SPI_FLASH=y
 CONFIG_DM_ETH=y
 CONFIG_ETH_DESIGNWARE=y