drm/i915: fixup runtime PM handling v2

According to the PCI docs and Rafael, we don't need to be doing explicit
enables and disables in our init and teardown routines, as they're taken
care of by the PCI core.  So drop the pm_runtime_disable() at teardown
and pm_runtime_set_active() at init.

This fixes one failure of the basic-pci-d3-state test on my BYT.

v2: drop extra get_noresume() and put_noidle() (Rafael)

Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_runtime_pm.c

@@ -1828,7 +1828,6 @@ static void intel_runtime_pm_disable(struct drm_i915_private *dev_priv)
 
 	/* Make sure we're not suspended first. */
 	pm_runtime_get_sync(device);
-	pm_runtime_disable(device);
 }
 
 /**
@@ -2120,8 +2119,6 @@ void intel_runtime_pm_enable(struct drm_i915_private *dev_priv)
 	if (!HAS_RUNTIME_PM(dev))
 		return;
 
-	pm_runtime_set_active(device);
-
 	/*
 	 * RPM depends on RC6 to save restore the GT HW context, so make RC6 a
 	 * requirement.