Extending BDW implementation to gen9. Pipe B/C interrupt
restoration after exiting LPSP.

v2: Fix minor rebasing conflict.
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>