This patch implements detection of SPT and SPT-LP PCH devices.

v2: Added HAS_PCH_SPT macro
Reviewed-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: NSatheeshakrishna M <satheeshakrishna.m@intel.com>
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>