slimbus: messaging: initialize completion correctly

slim_val_inf can contain random value from stack, make sure the completion
is initialized to NULL while filling the msg.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/slimbus/messaging.c

@@ -246,6 +246,7 @@ static void slim_fill_msg(struct slim_val_inf *msg, u32 addr,
 	msg->num_bytes = count;
 	msg->rbuf = rbuf;
 	msg->wbuf = wbuf;
+	msg->comp = NULL;
 }
 
 /**