Staging: udlfb: Rework startup and teardown to fix race conditions

Staging: udlfb: Rework startup and teardown to fix race conditions

Rework probe to use refcounts and std functions

Because the different parts of the driver (usb, fbdev) tear down
in different orders, the driver previously could crash accessing
data that had already been freed.  Refcounting system used to handle.

Reworked probe to make use of refcounts, set mode using std fbops,
and set up sysfs and pre-allocated urbs.

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