staging: comedi: addi_apci_3120: remove private data 'ai_running'
This member of the private data was used to determine if the interrupt
routine was handling data for the (*insn_read) or an async command. Now
that the (*insn_read) does not use interrupts this member is not needed.
Remove the member and refactor the code.
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>