drm/i915: Convert wait_for(I915_READ(reg)) to intel_wait_for_register()

By using the out-of-line intel_wait_for_register() not only do we can
efficiency from using the hybrid wait_for() contained within, but we
avoid code bloat from the numerous inlined loops, in total (all patches):

   text    data     bss     dec     hex filename
1078551    4557     416 1083524  108884 drivers/gpu/drm/i915/i915.ko
1070775    4557     416 1075748  106a24 drivers/gpu/drm/i915/i915.ko
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1467297225-21379-53-git-send-email-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_runtime_pm.c

@@ -1340,7 +1340,11 @@ static void chv_dpio_cmn_power_well_enable(struct drm_i915_private *dev_priv,
 	vlv_set_power_well(dev_priv, power_well, true);
 
 	/* Poll for phypwrgood signal */
-	if (wait_for(I915_READ(DISPLAY_PHY_STATUS) & PHY_POWERGOOD(phy), 1))
+	if (intel_wait_for_register(dev_priv,
+				    DISPLAY_PHY_STATUS,
+				    PHY_POWERGOOD(phy),
+				    PHY_POWERGOOD(phy),
+				    1))
 		DRM_ERROR("Display PHY %d is not power up\n", phy);
 
 	mutex_lock(&dev_priv->sb_lock);