This patch adds support for ACPI_TABLE_UPGRADE for ARM64

To access initrd image we need to move initialization
of linear mapping a bit earlier.

The implementation of the feature acpi_table_upgrade()
(drivers/acpi/tables.c) works with initrd data represented as an array
in virtual memory.  It uses some library utility to find the redefined
tables in that array and iterates over it to copy the data to new
allocated memory.  So to access the initrd data via fixmap
we need to rewrite it considerably.

In x86 arch, kernel memory is already mapped by the time when
acpi_table_upgrade() and acpi_boot_table_init() are called so I
think that we can just move this mapping one function earlier too.
Signed-off-by: Jon Masters <jcm@redhat.com>
Signed-off-by: Aleksey Makarov <aleksey.makarov@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>