staging: tidspbridge: Remove cfg_get_object()

As the services directory is going to be removed, the cfg_get_object
function has also to be removed.

Since the driver object handle is retrieved from the drv_data structure,
then the word "Registry" is replaced by "driver data" in the comments.

Also, the hdrv_obj is not used in function omap34_xx_bridge_remove(), so
it is removed.

Signed-off-by: Ivan Gomez Castellanos <ivan.gomez@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>