Staging: udlfb: clean up function naming

Move to more consistent naming scheme

All udlfb functions start with udlfb_
All functions for udlfb's fbdev interface start with udlfb_ops_
All functinos for udlfb's usb interface start with udlfb_usb_

Signed-off-by: Bernie Thompson <bernie@plugable.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>