x86/gpu: CNL uses the same GMS values as SKL

So don't forget to reserve its stolen memory bits.

v2: Add ack and remove "TODO" from commit message.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://patchwork.freedesktop.org/patch/msgid/1499302845-17856-1-git-send-email-rodrigo.vivi@intel.com