staging: comedi: vmk80xx: push usb (*probe) into comedi (*auto_attach)

Make the usb_driver (*probe) simply call comedi_usb_auto_config()
and move all the (*probe) code into the (*auto_attach) function.

This allows getting rid of the static private data array since we
no longer do part of the initialization in the (*probe) and then
finish it in the (*auto_attach). We can simply kzalloc the private
data instead. The comedi core will then handle the kfree of the
data when the driver is detached.

We can also get rid of the static 'glb_mutex' since this mutex was
only used to protect the static private data array.

Change the parameters for a couple of the helper functions used
during the auto attach. Now that the comedi_device is available
we can simply pass that pointer and get the specific pointers
needed by the helper functions from it.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>