staging: comedi: adl_pci9118: no need to reset ai FIFO after (*insn_read)

The analog input FIFO is reset at the start of every (*insn_read) and (*do_cmd)
operation. It's also reset for the analog input (*cancel).

There's no reason to reset the FIFO if an (*insn_read) times out or after
all the samples have been acquired.

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>