staging: comedi: Kconfig: menuconfig options should be bool

The menuconfig options to enable the various comedi driver types
should be bool not tristate. They don't directly affect the
building of the kernel, they just allow other options to be
selected.

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