staging: comedi: adv_pci1710: tidy up pci1710_reset()

Change the return type to void, this function always succeeds and the
caller does not check the return value anyway.

Fix the initial programming of the control register. The SW bit enables
the software trigger and should not be set here. Setting CNT0 selects the
external clock source for counter 0 (the user counter). It makes more
sense to select the internal 1 MHz clock.

Remove the unnecessary initialization of the private data members. This
function is only called during the (*auto_attach) after the private
data was kzalloc'ed.

Remove the redundant clearing of the A/D FIFO and pending interrupts.
Just do it once.

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