staging: comedi: addi_apci_3120: rename private data 'us_UseDma'

Rename this CamelCase member of the private data and convert it to
a bit-field.

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>
2 files changed