staging: comedi: adl_pci9118: do cfc_handle_events() at end of interrupt

Each of the error detections currently do a cfc_handle_events() and exits
the interrupt handler if the error is detected. The DMA and non-DMA handlers
also to a cfc_handle_events().

For aesthetics, use goto to exit the interrupt handler if an error is detected
and move the cfc_handle_events() call to the end of the interrupt.

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>