drm/i915: Store a i915 backpointer from engine, and use it

   text	   data	    bss	    dec	    hex	filename
6309351	3578714	 696320	10584385	 a18141	vmlinux
6308391	3578714	 696320	10583425	 a17d81	vmlinux

Almost 1KiB of code reduction.

v2: More s/INTEL_INFO()->gen/INTEL_GEN()/ and IS_GENx() conversions

   text	   data	    bss	    dec	    hex	filename
6304579	3578778	 696320	10579677	 a16edd	vmlinux
6303427	3578778	 696320	10578525	 a16a5d	vmlinux

Now over 1KiB!

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1462545621-30125-3-git-send-email-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index ca9bea6..a116730 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -530,9 +530,9 @@
 	pci_dev_put(pch);
 }
 
-bool i915_semaphore_is_enabled(struct drm_device *dev)
+bool i915_semaphore_is_enabled(struct drm_i915_private *dev_priv)
 {
-	if (INTEL_INFO(dev)->gen < 6)
+	if (INTEL_GEN(dev_priv) < 6)
 		return false;
 
 	if (i915.semaphores >= 0)
@@ -544,7 +544,7 @@
 
 #ifdef CONFIG_INTEL_IOMMU
 	/* Enable semaphores on SNB when IO remapping is off */
-	if (INTEL_INFO(dev)->gen == 6 && intel_iommu_gfx_mapped)
+	if (IS_GEN6(dev_priv) && intel_iommu_gfx_mapped)
 		return false;
 #endif
 
@@ -914,9 +914,9 @@
  *   - re-init interrupt state
  *   - re-init display
  */
-int i915_reset(struct drm_device *dev)
+int i915_reset(struct drm_i915_private *dev_priv)
 {
-	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_device *dev = dev_priv->dev;
 	struct i915_gpu_error *error = &dev_priv->gpu_error;
 	unsigned reset_counter;
 	int ret;