staging: comedi: ni_mio_common: simplify AI LINKC handling

Simplfy the LINKC handing for the analog input dma by moving it into
the main interrupt handler. This function already hold the spinlock
mite_channel_lock so call mite_sync_dma() directly instead of using
the helper function.

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>