staging: comedi: ni_65xx: disable edge detection on initialization

When the hardware is being initialized, the edge detection interrupts
are cleared and disabled.  Also disable edge detection for all channels
at this time so they start off in a known state.

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