drm: Extract drm_drv.h

I want to move dumb buffer documentation into the right vfuncs, and
for that I first need to be able to pull that into kerneldoc without
having to clean up all of drmP.h. Also, header-splitting is nice.

While at it shuffle all the function declarations for drm_drv.c into
the right spots, and drop the kerneldoc for drm_minor_acquire/release
since it's only used internally.

v2: Keep all existing copyright notices (Chris).

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
index abd2098..b8cc0fc 100644
--- a/drivers/gpu/drm/drm_internal.h
+++ b/drivers/gpu/drm/drm_internal.h
@@ -46,6 +46,10 @@ void drm_prime_destroy_file_private(struct drm_prime_file_private *prime_fpriv);
 void drm_prime_remove_buf_handle_locked(struct drm_prime_file_private *prime_fpriv,
 					struct dma_buf *dma_buf);
 
+/* drm_drv.c */
+struct drm_minor *drm_minor_acquire(unsigned int minor_id);
+void drm_minor_release(struct drm_minor *minor);
+
 /* drm_info.c */
 int drm_name_info(struct seq_file *m, void *data);
 int drm_clients_info(struct seq_file *m, void* data);