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/1467297225-21379-43-git-send-email-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_psr.c

@@ -501,8 +501,11 @@ static void vlv_psr_disable(struct intel_dp *intel_dp)
 
 	if (dev_priv->psr.active) {
 		/* Put VLV PSR back to PSR_state 0 that is PSR Disabled. */
-		if (wait_for((I915_READ(VLV_PSRSTAT(intel_crtc->pipe)) &
-			      VLV_EDP_PSR_IN_TRANS) == 0, 1))
+		if (intel_wait_for_register(dev_priv,
+					    VLV_PSRSTAT(intel_crtc->pipe),
+					    VLV_EDP_PSR_IN_TRANS,
+					    0,
+					    1))
 			WARN(1, "PSR transition took longer than expected\n");
 
 		val = I915_READ(VLV_PSRCTL(intel_crtc->pipe));