Revert "drm/i915/bxt: Disable power well support"

With the preceding fixes power well support should be functional on
Broxton, I could enter/exit DC5 without problems.

This reverts commit 18024199579882265653bfe9e2b1a3dcb5697cd9.

CC: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: David Weinehall <david.weinehall@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459515767-29228-16-git-send-email-imre.deak@intel.com

drivers/gpu/drm/i915/intel_runtime_pm.c

@@ -1963,11 +1963,6 @@ sanitize_disable_power_well_option(const struct drm_i915_private *dev_priv,
 	if (disable_power_well >= 0)
 		return !!disable_power_well;
 
-	if (IS_BROXTON(dev_priv)) {
-		DRM_DEBUG_KMS("Disabling display power well support\n");
-		return 0;
-	}
-
 	return 1;
 }