staging: comedi: skel: replace pr_...() with dev_...()

Use the dev_info() etc. instead of pr_info() etc.  Remove a couple of
them that seemed a bit pointless.

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