staging: ipu-v3: ipu-common: Indicate succesful probe

Indication of succesful probe is more useful than stating that the
driver is about to be probed.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>