greybus: convert drivers to use connection->private set/get

This converts all drivers to use the gb_connection_get_data() and
gb_connection_set_data() functions to make it a bit more explicit as to
what is going on.

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
diff --git a/drivers/staging/greybus/vibrator.c b/drivers/staging/greybus/vibrator.c
index 8c0df99..5afcb27 100644
--- a/drivers/staging/greybus/vibrator.c
+++ b/drivers/staging/greybus/vibrator.c
@@ -114,7 +114,7 @@
 		retval = PTR_ERR(connection);
 		goto err_free_vib;
 	}
-	connection->private = vib;
+	gb_connection_set_data(connection, vib);
 
 	vib->connection = connection;