bus: mvebu-mbus: make iounmap() symmetric with ioremap()

make coccicheck complains:

  ./drivers/bus/mvebu-mbus.c:1113:2-8: ERROR: missing iounmap; ioremap on line 1106 and execution via conditional on line 1111

It took some staring but I don't think there is a problem because the
file global `mbus_state` is passed mvebu_mbus_common_init() as the
`mbus` parameter so `mbus_state.mbuswins_base` and `mbus->mbuswins_base`
are the same thing. But this is confusing for anyone reading the code
and one less complaint from coccicheck would be nice so lets fix it.
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Acked-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>

drivers/bus/mvebu-mbus.c

@@ -1111,7 +1111,7 @@ static int __init mvebu_mbus_common_init(struct mvebu_mbus_state *mbus,
 
 	mbus->sdramwins_base = ioremap(sdramwins_phys_base, sdramwins_size);
 	if (!mbus->sdramwins_base) {
-		iounmap(mbus_state.mbuswins_base);
+		iounmap(mbus->mbuswins_base);
 		return -ENOMEM;
 	}