staging: comedi: ke_counter: tidy up the subdevice init

For aesthetics, add some whitespace to the subdevice init.

This driver does not support async commands so remove the dev->read_subdev
initialization.

Remove the commented out SDF_COMMON from the subdevice subev_flags.

Add the subdevice range_table initialization.

For aesthetics, rename the (*insn_{read,write}) functions so they have
namespace associated with the driver.

Remove the unnecessary comments about the (*insn_{read,write}) functions.

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>