slimbus: messaging: pass correct wbuf

There seems to be a typo while filling msg for slim_write, wbuf is
set to NULL instead of rbuf.
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/slimbus/messaging.c

@@ -307,7 +307,7 @@ int slim_write(struct slim_device *sdev, u32 addr, size_t count, u8 *val)
 {
 	struct slim_val_inf msg;
 
-	slim_fill_msg(&msg, addr, count,  val, NULL);
+	slim_fill_msg(&msg, addr, count,  NULL, val);
 
 	return slim_xfer_msg(sdev, &msg, SLIM_MSG_MC_CHANGE_VALUE);
 }