staging: comedi: comedi.h: remove SDF_MODE0 etc.

The macros `SDF_MODE0`, `SDF_MODE1`, `SDF_MODE2`, `SDF_MODE3`, and
`SDF_MODE4` are COMEDI subdevice flags originally associated with the
obsolete (and no longer present) COMEDI "trigger" functionality.  They
have been of no use since COMEDI release 0.7.61 back in November 2001.
Since they were going spare, a couple of them have been aliased as
`SDF_PWM_COUNTER` and `SDF_PWM_HBRIDGE` to mean other things.  Remove
the obsolete macros and redefine `SDF_PWM_COUNTER` and `SDF_PWM_HBRIDGE`
as equivalent numeric values.

Some code distributed with the userspace COMEDILIB library uses the
`SDF_MODE0` etc. flags to display the fact that they are set, but
COMEDILIB uses and installs its own, compatible version of "comedi.h"
anyway so isn't affected by their removal from the kernel copy.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>