acpi-build: fix ACPI RAM management

acpi-build: fix ACPI RAM management

This fixes multiple issues around ACPI RAM management:

RSDP and linker RAM aren't currently marked dirty
on update, so they won't be migrated correctly.

Let's handle all tables in the same way: set correct size (assert if
too big), update, mark RAM dirty.

This also drops assert checking that table size didn't change: table
size is fundamentally dynamic and depends on hw configuration,
just set the correct size and use that (memory core asserts if size is
too large).

This also means we can drop tracking table size, memory core does this
for us now.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>