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/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index b37a042..8ff7114 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1231,8 +1231,8 @@
 			      const struct drm_framebuffer *fb, int plane,
 			      unsigned int pitch,
 			      unsigned int rotation);
-void intel_prepare_reset(struct drm_device *dev);
-void intel_finish_reset(struct drm_device *dev);
+void intel_prepare_reset(struct drm_i915_private *dev_priv);
+void intel_finish_reset(struct drm_i915_private *dev_priv);
 void hsw_enable_pc8(struct drm_i915_private *dev_priv);
 void hsw_disable_pc8(struct drm_i915_private *dev_priv);
 void broxton_init_cdclk(struct drm_i915_private *dev_priv);