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/1467297225-21379-9-git-send-email-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_ddi.c

@@ -1808,7 +1808,10 @@ static u32 bxt_get_grc(struct drm_i915_private *dev_priv, enum dpio_phy phy)
 static void bxt_phy_wait_grc_done(struct drm_i915_private *dev_priv,
 				  enum dpio_phy phy)
 {
-	if (wait_for(I915_READ(BXT_PORT_REF_DW3(phy)) & GRC_DONE, 10))
+	if (intel_wait_for_register(dev_priv,
+				    BXT_PORT_REF_DW3(phy),
+				    GRC_DONE, GRC_DONE,
+				    10))
 		DRM_ERROR("timeout waiting for PHY%d GRC\n", phy);
 }