staging: comedi: das16: cleanup comedi_error() messages

Some of these messages are missing the terminating '\n' and most of them
have the quoted string split across lines.

Change all of them to dev_err() messages and fix the issues.

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>