x86: zImage: Propagate acpi_rsdp_addr to kernel via boot parameters

x86: zImage: Propagate acpi_rsdp_addr to kernel via boot parameters

This is reincarnation of the U-Boot

commit 941d69ade7cfd63538e93fbb85bcb99199485edc
Author: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Date:   Wed Jan 10 19:40:15 2018 +0200

    x86: zImage: Propagate acpi_rsdp_addr to kernel via boot parameters

after upstream got eventually the Linux kernel

commit e6e094e053af75cbc164e950814d3d084fb1e698
Author: Juergen Gross <jgross@suse.com>
Date:   Tue Nov 20 08:25:29 2018 +0100

    x86/acpi, x86/boot: Take RSDP address from boot params if available

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>