staging: comedi: adl_pci9118: fix interrupt_pci9118_ai_mode4_switch()

This function modifies the analog input acquistion programming after the first
DMA cycle to continue a "mode4" acqusition. Part of this programs timer 0 based
on the hardware address of the next buffer. When double buffering is not used
for DMA the "next" buffer is always the first, and only, buffer.

Add a parameter to this function to indicate what the "next" buffer actually is
and fix the callers.

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>