drm/i915/gen9: Correct max save/restore register count during gpu reset with GuC

drm/i915/gen9: Correct max save/restore register count during gpu reset with GuC

In GuC submission mode, driver has to provide a list of registers to be
save/restored during gpu reset, make the max no. of registers value consistent
with that of the value defined in FW. If they are not in sync then register
save/restore during gpu reset won't work as expected.

Cc: Alex Dai <yu.dai@intel.com>
Cc: Dave Gordon <david.s.gordon@intel.com>
Signed-off-by: Arun Siluvery <arun.siluvery@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1453132776-22229-1-git-send-email-arun.siluvery@linux.intel.com
Reviewed-by: Alex Dai <yu.dai@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>