staging: comedi: ni_mio_common: tidy up the Analog Input subdevice init

For aesthetics, add some whitespace to the Analog Input subdevice init.

The callers of ni_E_init() do the request_irq() and set dev->irq if the
interrupt is available. Only hook up the async command support if we
have the irq.

Also, remove the '#ifdef PCIDMA' here. The ni_pcimio driver is the only
place PCIDMA is defined. That driver is also the only user of ni_mio_common
that allocates devpriv->mite. Use that test instead to determine if the
subdevice async_dma_dir member needs to be initialized.

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>