DRM / i915: Fix resume regression on MSI Wind U100 w/o KMS

Commit cbda12d7 (drm/i915: implement
new pm ops for i915), among other things, removed the .suspend and
.resume pointers from the struct drm_driver object in i915_drv.c,
which broke resume without KMS on my MSI Wind U100.

Fix this by reverting that part of commit cbda12d7.

[ The DRM layer will not use the class-specific suspend/resume functions
  if the driver is marked MODESET-aware, and conversely it will not
  register the PCI device if the drievr isn't so marked, so you always
  end up with _either_ the drm-class suspend/resume _or_ the PCI layer
  PM functionality, never both.  - Linus ]
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/gpu/drm/i915/i915_drv.c

@@ -464,6 +464,8 @@ static struct drm_driver driver = {
 	.lastclose = i915_driver_lastclose,
 	.preclose = i915_driver_preclose,
 	.postclose = i915_driver_postclose,
+	.suspend = i915_suspend,
+	.resume = i915_resume,
 	.device_is_agp = i915_driver_device_is_agp,
 	.enable_vblank = i915_enable_vblank,
 	.disable_vblank = i915_disable_vblank,