drm/i915/aml: Allow SPT PCH for all AML devices

Even the AML devices that behave like CFLs can be paired with an SPT
PCH. Allow this to happen without blowing up dmesg.

BSpec: 33665

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112013


Cc: Quanxian Wang <quanxian.wang@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: James Ausmus <james.ausmus@intel.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191017194203.9645-1-james.ausmus@intel.com