x86/kexec: Fill in acpi_rsdp_addr from the first kernel

When efi=noruntime or efi=oldmap is used on the kernel command line, EFI
services won't be available in the second kernel, therefore the second
kernel will not be able to get the ACPI RSDP address from firmware by
calling EFI services and so it won't boot.

Commit

  e6e094e0 ("x86/acpi, x86/boot: Take RSDP address from boot params if available")

added an acpi_rsdp_addr field to boot_params which stores the RSDP
address for other kernel users.

Recently, after

  3a63f70b

 ("x86/boot: Early parse RSDP and save it in boot_params")

the acpi_rsdp_addr will always be filled with a valid RSDP address.

So fill in that value into the second kernel's boot_params thus ensuring
that the second kernel receives the RSDP value from the first kernel.

 [ bp: massage commit message. ]

Signed-off-by: Kairui Song <kasong@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Chao Fan <fanc.fnst@cn.fujitsu.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: kexec@lists.infradead.org
Cc: Philipp Rudo <prudo@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Cc: Yannik Sembritzki <yannik@sembritzki.me>
Link: https://lkml.kernel.org/r/20190204173852.4863-1-kasong@redhat.com