drm/i915/vlv: Prevent enabling hpd polling in late suspend

drm/i915/vlv: Prevent enabling hpd polling in late suspend

One of the CI machines began to run into issues with the hpd poller
suddenly waking up in the midst of the late suspend phase. It looks like
this is getting caused by the fact we now deinitialize power wells in
late suspend, which means that intel_hpd_poll_init() gets called in late
suspend causing polling to get re-enabled. So, when deinitializing power
wells on valleyview we now refrain from enabling polling in the midst of
suspend.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98040
Fixes: 4c53a4c67ed9 ("drm/i915: Enable polling when we don't have hpd")
Signed-off-by: Lyude <lyude@redhat.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Jani Saarinen <jani.saarinen@intel.com>
Cc: Petry Latvala <petri.latvala@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1477499769-1966-1-git-send-email-lyude@redhat.com
(cherry picked from commit b64b540931483cca3200d98756bed6ad0e01d75c)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>