staging: vt6655: use netdev_* instead of printk

Checkpatch.pl gave the following warnings

WARNING: printk() should include KERN_ facility level

After fixing these with KERN_INFO facility level, it was suggested to
use netdev_ instead of printk() with KERN_INFO facility.
Used netdev_dbg for the statements inside of PLICE_DEBUG #ifdef, as
debugging shouldn't rely on compile options and netdev_info for one
printk which wasn't inside any #ifdef PLICE_DEBUG.

Signed-off-by: Teodora Baluta <teobaluta@gmail.com>
Reviewed-by: Lisa Nguyen <lisa@xenapiadmin.com>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>