staging: pi433: Replace printk() with dev_dbg()

This patch convert printk() to the preferred variant dev_dbg() and
remove unnecessary comment line.
Issue detected with checkpatch.pl.

Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>