staging: comedi: acl7225b: dev->irq is already '0'

This driver does not use interrupts and the dev->irq variable is
already set to '0' when then (*attach) function is called. Setting
it in the driver is unnecessary.

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