staging: comedi: comedi_test: remove use of comedi_error()

The comedi_error() function is just a wrapper around dev_err() that adds
the dev->driver->driver_name prefix to the message and a terminating
new-line character. The addition of the driver_name is just added noise
and some of the users of comedi_error() add unnecessary additional new-line
characters.

Use dev_err() directly instead of comedi_error() to avoid any confusion
and so that all the comedi generated kernel messages have the same format.

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>