powerpc: sysdev: add missing iounmap() on error in mpic_msgr_probe()

I noticed that iounmap() of msgr_block_addr before return from
mpic_msgr_probe() in the error handling case is missing. So use
devm_ioremap() instead of just ioremap() when remapping the message
register block, so the mapping will be automatically released on
probe failure.
Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201028091551.136400-1-miaoqinglang@huawei.com

arch/powerpc/sysdev/mpic_msgr.c

@@ -191,7 +191,7 @@ static int mpic_msgr_probe(struct platform_device *dev)
 
 	/* IO map the message register block. */
 	of_address_to_resource(np, 0, &rsrc);
-	msgr_block_addr = ioremap(rsrc.start, resource_size(&rsrc));
+	msgr_block_addr = devm_ioremap(&dev->dev, rsrc.start, resource_size(&rsrc));
 	if (!msgr_block_addr) {
 		dev_err(&dev->dev, "Failed to iomap MPIC message registers");
 		return -EFAULT;