drm: Move __drm_pci_free to drm_legacy.h

Also sprinkle the customary legacy_ prefix.

Unfortunately we can't move the other functions since i915 is still
using them. Shame on me for that one :(

v2: Fix patch subject as spotted by David Herrmann.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/include/drm/drm_legacy.h b/include/drm/drm_legacy.h
index 605d660..9862631 100644
--- a/include/drm/drm_legacy.h
+++ b/include/drm/drm_legacy.h
@@ -55,4 +55,7 @@
 void drm_legacy_idlelock_take(struct drm_lock_data *lock);
 void drm_legacy_idlelock_release(struct drm_lock_data *lock);
 
+/* drm_pci.c dma alloc wrappers */
+void __drm_legacy_pci_free(struct drm_device *dev, drm_dma_handle_t * dmah);
+
 #endif /* __DRM_DRM_LEGACY_H__ */