drm: move drm_class into drm_sysfs.c

Right now, drm_sysfs_create() returns the newly allocated "struct class"
to the caller (which is drm_core_init()), which then has to set the
global variable 'drm_class'. During cleanup, though, we call
drm_sysfs_destroy() which implicitly uses the global 'drm_class'. This is
confusing, as ownership of the global 'drm_class' is non-obvious.

This patch changes drm_sysfs_create() to drm_sysfs_init() and makes it
initialize the 'drm_class' object directly, rather than returning it.
This way, both drm_sysfs_init() and drm_sysfs_destroy() work in a similar
fashion and manage the global drm class.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
index 059af01..43cbda3 100644
--- a/drivers/gpu/drm/drm_internal.h
+++ b/drivers/gpu/drm/drm_internal.h
@@ -73,7 +73,7 @@
 /* drm_sysfs.c */
 extern struct class *drm_class;
 
-struct class *drm_sysfs_create(struct module *owner, char *name);
+int drm_sysfs_init(void);
 void drm_sysfs_destroy(void);
 struct device *drm_sysfs_minor_alloc(struct drm_minor *minor);
 int drm_sysfs_connector_add(struct drm_connector *connector);