staging: comedi: addi_apci_2032: correct interrupt subdevice

The subdevice type and flags are initialized incorrectly for the
interrupt subdevice - the SDF_CMD_READ value belongs in the subdevice
flags.  Fix it.  Also set the number of channels to 2 since there are 2
interrupt sources each with its own status bit.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>