DPIO needs to have common reset de-asserted on soft resets like boot and
S3.  In some cases, the BIOS will have done this for us, but it should
be safe to do at runtime as well, as long as we do it when the pipes are
otherwise off.

v2: update bit name to match docs better (Ville)
    reset after CRI clock select (Ville)

References: https://bugs.freedesktop.org/show_bug.cgi?id=69166


Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>