drm/drv: Fix incorrect resolution of merge conflict

Commit f06ddb53 ("BackMerge v5.1-rc5 into drm-next") incorrectly
resolved a merge conflict related to a patch having been merged twice:
- commit 3f04e0a6 ("drm: Fix drm_release() and device unplug")
  introduced as a standalone fix via drm-fixes branch,
- commit 1ee57d4d ("drm: Fix drm_release() and device unplug")
  applied as patch 1/2 of a series on drm-next branch.
That incorrect resolution of the conflict effectively reverted a change
introduced to drivers/gpu/drm/drm_drv.c by patch 2/2 of that series -
commit ba3bf37e ("drm/drv: drm_dev_unplug(): Move out drm_dev_put()
call").  Fix it.

Fixes: f06ddb53 ("BackMerge v5.1-rc5 into drm-next")
Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190417133232.16232-1-janusz.krzysztofik@linux.intel.com

drivers/gpu/drm/drm_drv.c

@@ -508,7 +508,6 @@ void drm_dev_unplug(struct drm_device *dev)
 	synchronize_srcu(&drm_unplug_srcu);
 
 	drm_dev_unregister(dev);
-	drm_dev_put(dev);
 }
 EXPORT_SYMBOL(drm_dev_unplug);