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/1467297225-21379-61-git-send-email-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_uncore.c

@@ -1553,20 +1553,16 @@ static int ironlake_do_reset(struct drm_i915_private *dev_priv,
 static int gen6_hw_domain_reset(struct drm_i915_private *dev_priv,
 				u32 hw_domain_mask)
 {
-	int ret;
-
 	/* GEN6_GDRST is not in the gt power well, no need to check
 	 * for fifo space for the write or forcewake the chip for
 	 * the read
 	 */
 	__raw_i915_write32(dev_priv, GEN6_GDRST, hw_domain_mask);
 
-#define ACKED ((__raw_i915_read32(dev_priv, GEN6_GDRST) & hw_domain_mask) == 0)
 	/* Spin waiting for the device to ack the reset requests */
-	ret = wait_for(ACKED, 500);
-#undef ACKED
-
-	return ret;
+	return intel_wait_for_register_fw(dev_priv,
+					  GEN6_GDRST, hw_domain_mask, 0,
+					  500);
 }
 
 /**