staging: comedi: comedi_fops: remove remaining BUG_ON() checks

The BUG_ON() checks in comedi_subdevice_from_minor() and
comedi_dev_get_from_subdevice_minor() are not necessary.

The 'minor' numbers for a given comedi driver are setup by
comedi_dev_get_from_subdevice_minor() and will always be in
the correct range.

Drivers should not crash the kernel, remove the BUG_ON() checks.

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