drm/i915: Reinit polling before hpd when resuming

Now that we don't run the connector reprobing from i915_drm_resume(), we
need to make it so we don't have to wait for reprobing to finish so that
we actually speed things up. In order to do this, we need to make sure
that i915_drm_resume() doesn't get blocked by i915_hpd_poll_init_work()
while trying to acquire the mode_config lock that
drm_kms_helper_poll_enable() needs to acquire.

The easiest way to do this is to just enable polling before hpd. This
shouldn't break anything since at that point we have everything else we
need for polling enabled.

As well, this should result in a rather significant improvement in how
quickly we can resume the system.

Signed-off-by: Lyude <lyude@redhat.com>
Tested-by: David Weinehall <david.weinehall@linux.intel.com>
Reviewed-by: David Weinehall <david.weinehall@linux.intel.com>
Testcase: analyze_suspend.py -config config/suspend-callgraph.cfg -filter i915