drm/i915: clean up unused ring_get_irq/ring_put_irq functions

This patch depends on patch "drm/i915: fix user irq miss in BSD ring on
g4x".
Once the previous patch apply, ring_get_irq/ring_put_irq become unused.
So simply remove them.
Signed-off-by: NFeng, Boqun <boqun.feng@intel.com>
Reviewed-by: NXiang, Haihao <haihao.xiang@intel.com>
Signed-off-by: NKeith Packard <keithp@keithp.com>

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -620,35 +620,6 @@ ring_add_request(struct intel_ring_buffer *ring,
 	return 0;
 }
 
-static bool
-ring_get_irq(struct intel_ring_buffer *ring, u32 flag)
-{
-	struct drm_device *dev = ring->dev;
-	drm_i915_private_t *dev_priv = dev->dev_private;
-
-	if (!dev->irq_enabled)
-	       return false;
-
-	spin_lock(&ring->irq_lock);
-	if (ring->irq_refcount++ == 0)
-		ironlake_enable_irq(dev_priv, flag);
-	spin_unlock(&ring->irq_lock);
-
-	return true;
-}
-
-static void
-ring_put_irq(struct intel_ring_buffer *ring, u32 flag)
-{
-	struct drm_device *dev = ring->dev;
-	drm_i915_private_t *dev_priv = dev->dev_private;
-
-	spin_lock(&ring->irq_lock);
-	if (--ring->irq_refcount == 0)
-		ironlake_disable_irq(dev_priv, flag);
-	spin_unlock(&ring->irq_lock);
-}
-
 static bool
 gen6_ring_get_irq(struct intel_ring_buffer *ring, u32 gflag, u32 rflag)
 {