x86/platform/UV: Add obtaining GAM Range Table from UV BIOS

UV4 uses a GAM (globally addressed memory) architecture that supports
variable sized memory per node.  This replaces the old "M" value (number
of address bits per node) with a range table for conversions between
addresses and physical node (pnode) id's.  This table is obtained from UV
BIOS via the EFI UVsystab table.  Support for older EFI UVsystab tables
is maintained.

Tested-by: Dimitri Sivanich <sivanich@sgi.com>
Tested-by: John Estabrook <estabrook@sgi.com>
Tested-by: Gary Kroening <gfk@sgi.com>
Tested-by: Nathan Zimmer <nzimmer@sgi.com>
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Andrew Banman <abanman@sgi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russ Anderson <rja@sgi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160429215405.329827545@asylum.americas.sgi.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>