armv8: ls2085a: Add support of random MAC address

Add support of setting RANDOM MAC address if env variable not available.

Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: York Sun <yorksun@freescale.com>
diff --git a/configs/ls2085aqds_nand_defconfig b/configs/ls2085aqds_nand_defconfig
index 10eda97..ce2a81c 100644
--- a/configs/ls2085aqds_nand_defconfig
+++ b/configs/ls2085aqds_nand_defconfig
@@ -3,5 +3,6 @@
 CONFIG_SPL=y
 CONFIG_SYS_EXTRA_OPTIONS="SYS_FSL_DDR4,NAND"
 # CONFIG_CMD_SETEXPR is not set
+CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_NETDEVICES=y
 CONFIG_E1000=y