x86/gpu: reserve ICL's graphics stolen memory

x86/gpu: reserve ICL's graphics stolen memory

ICL changes the registers and addresses to 64 bits.

I also briefly looked at implementing an u64 version of the PCI config
read functions, but I concluded this wouldn't be trivial, so it's not
worth doing it for a single user that can't have any racing problems
while reading the register in two separate operations.

v2:
 - Scrub the development (non-public) changelog (Joonas).
 - Remove the i915.ko bits so this can be easily backported in order
   to properly avoid stolen memory even on machines without i915.ko
   (Joonas).
 - CC stable for the reasons above.

Issue: VIZ-9250
CC: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: x86@kernel.org
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Fixes: 412310019a20 ("drm/i915/icl: Add initial Icelake definitions.")
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180504203252.28048-1-paulo.r.zanoni@intel.com