staging: comedi: pcl818: fix board resource region request

Some of the PCL-818 compatible boards have a FIFO that can be used
when running analog input async commands. This FIFO increased the
resource range used by the driver.

Request the correct resources used by the board even if the FIFO is
not used. This prevents another driver from trying to use the I/O
space.

Modify the attach so that the 'usefifo' flag is only set if we have
and IRQ, the board has a FIFO, and the user wahts to use it.

Fix pcl818_reset() so that the FIFO is always flushed and disabled
if it exists.

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>