Revert "drm/gem: Warn on illegal use of the dumb buffer interface v2"

This reverts commit 355a70183848f21198e9f6296bd646df3478a26d.

This had some bad side effects under normal operation, and should
have been dropped earlier.

Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 63bcda5..70d0f0f 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2501,9 +2501,8 @@
 int i915_gem_dumb_create(struct drm_file *file_priv,
 			 struct drm_device *dev,
 			 struct drm_mode_create_dumb *args);
-int i915_gem_dumb_map_offset(struct drm_file *file_priv,
-			     struct drm_device *dev, uint32_t handle,
-			     uint64_t *offset);
+int i915_gem_mmap_gtt(struct drm_file *file_priv, struct drm_device *dev,
+		      uint32_t handle, uint64_t *offset);
 /**
  * Returns true if seq1 is later than seq2.
  */