riscv: sifive: fu540: set serial environment variable from otp

This patch sets the serial# environment variable by reading the
board serial number from the OTP memory region.

Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
1 file changed