provide no methods does not make any sense, and is not used by any
driver.
It is a pretty hard to come up with even a theoretical concept of
a device driver which would always fail open and close with ENODEV.
Change the defaults to be nullopen() and nullclose() which simply
does nothing.
Remove explicit initializations to these from the drivers which
already used them.
Boost sample rate to 1.25 MSPS since that allows us to use a 5Mhz
(/4) or 10Mhz (/8) external clock.
Make the interrupt both MPSAFE and FAST, at 610 interrupts a second,
and a max time to service of 5 msec, we brake for nobody.
Use kernel thread to accumulate into the 25 possible wave signals.
Use #ifdef _KERNEL to let .c file double as .h file defining the ioctls.
