staging: comedi: ni_670x: change printk's to cleaned up dev_printk's

Convert all the prink's in this file to dev_prink's.

Change the INFO message in ni_670x_find_device into a dev_warn().
This message is only displayed if a matching device was not found.
A warning is more appropriate here than info.

Consolidate the attach messages into one dev_info() output after
the successful attach.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>