drm/i915/aml: Introducing Amber Lake platform

Amber Lake uses the same gen graphics as Kaby Lake, including a id
that were previously marked as reserved on Kaby Lake, but that
now is moved to AML page.

So, let's just move it to AML macro that will feed into KBL macro
just to keep it better organized to make easier future code review
but it will be handled as a KBL.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180614233720.30517-2-jose.souza@intel.com