staging: comedi: multiq3: tidy up control register bit defines

For aesthetics, move these defines closer to the register define and
use the BIT macro to define the bits.

Add macros to set the bits needed to select the channel for the analog
output, analog input, and encoder (counter) subdevices as well as the
realtime clock registers.

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