Check ISST (Intel SpeedShift) availability via CPUID.06H:EAX[7], instead
of relying on the devicetree option `speed_shift_enable`, that is going
to be dropped.
Test: GCPC and _CPC entries still get generated on Supermicro X11SSM-F
Change-Id: I5f9bf09385627fb6a1d8e566a80370f7ddd8605e
Signed-off-by: Michael Niewöhner <foss@mniewoehner.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/46461
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Felix Singer <felixsinger@posteo.net>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>