staging: dgnc: cleanup dgnc_finalize_board_init()

Trivial cleanups:
- Transform a printk() to a dev_err() call
- Fix 2 lines over 80 characters

Signed-off-by: Antoine Sirinelli <antoine@monte-stello.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>