uboot-imx

riscv: bootm: Pass mhartid CSR value to kernel

So far this is hardcoded to zero, and we should read the value from
mhartid CSR and pass it to Linux kernel.

Suggested-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Rick Chen <rick@andestech.com>