x86/gpu: add TGL stolen memory support

x86/gpu: add TGL stolen memory support

Reuse Gen11 stolen memory changes since Tiger Lake uses the same BSM
register (and format).

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Signed-off-by: Michel Thierry <michel.thierry@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20190712210238.5622-1-lucas.demarchi@intel.com