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/1467297225-21379-7-git-send-email-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_crt.c

@@ -340,7 +340,9 @@ static bool valleyview_crt_detect_hotplug(struct drm_connector *connector)
 
 	I915_WRITE(crt->adpa_reg, adpa);
 
-	if (wait_for((I915_READ(crt->adpa_reg) & ADPA_CRT_HOTPLUG_FORCE_TRIGGER) == 0,
+	if (intel_wait_for_register(dev_priv,
+				    crt->adpa_reg,
+				    ADPA_CRT_HOTPLUG_FORCE_TRIGGER, 0,
 				    1000)) {
 		DRM_DEBUG_KMS("timed out waiting for FORCE_TRIGGER");
 		I915_WRITE(crt->adpa_reg, save_adpa);