drm/i915: Remove I915_POSTING_READ_FW

Only a few call sites remain which have been converted to uncore mmio
accessors and so the macro can be removed.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190611104548.30545-2-tvrtko.ursulin@linux.intel.com
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 17e8809..4017ecf 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -263,11 +263,12 @@ void i915_gem_flush_ggtt_writes(struct drm_i915_private *dev_priv)
 	i915_gem_chipset_flush(dev_priv);
 
 	with_intel_runtime_pm(dev_priv, wakeref) {
-		spin_lock_irq(&dev_priv->uncore.lock);
+		struct intel_uncore *uncore = &dev_priv->uncore;
 
-		POSTING_READ_FW(RING_HEAD(RENDER_RING_BASE));
-
-		spin_unlock_irq(&dev_priv->uncore.lock);
+		spin_lock_irq(&uncore->lock);
+		intel_uncore_posting_read_fw(uncore,
+					     RING_HEAD(RENDER_RING_BASE));
+		spin_unlock_irq(&uncore->lock);
 	}
 }