layerscape: Fix check after kernel update

The fsl_destroy_mc_io() function was moved, add the new checks to the
moved copy and not just remove it.

Fixes: ac5297340e ("kernel: bump 4.14 to 4.14.206")
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

target/linux/layerscape/patches-4.14/708-mc-bus-support-layerscape.patch

@@ -8911,7 +8911,7 @@ Signed-off-by: Stuart Yoder <stuart.yoder@nxp.com>
 -EXPORT_SYMBOL_GPL(fsl_mc_portal_reset);
 --- /dev/null
 +++ b/drivers/bus/fsl-mc/mc-io.c
-@@ -0,0 +1,281 @@
+@@ -0,0 +1,286 @@
 +// SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
 +/*
 + * Copyright 2013-2016 Freescale Semiconductor Inc.
@@ -9043,7 +9043,12 @@ Signed-off-by: Stuart Yoder <stuart.yoder@nxp.com>
 + */
 +void fsl_destroy_mc_io(struct fsl_mc_io *mc_io)
 +{
-+	struct fsl_mc_device *dpmcp_dev = mc_io->dpmcp_dev;
++	struct fsl_mc_device *dpmcp_dev;
++
++	if (!mc_io)
++		return;
++
++	dpmcp_dev = mc_io->dpmcp_dev;
 +
 +	if (dpmcp_dev)
 +		fsl_mc_io_unset_dpmcp(mc_io);