Split ACPI boot table parsing

Split ACPI boot table parsing into two parts.  First a acpi_boot_table_init()
call that initializes the basic ACPI table parsing machinery and discovers the
RSDP, and then another call to actually parse the various boot tables.

This is needed for a followon patch that implements SRAT support, because
nodes need to be set up before the other ACPI tables can be parsed.

On x86-64 I moved the early initialization very early because that is needed
for the SRAT parser.

On i386 it should be a nop.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>