omap: mailbox: check iomem resource before dereferencing it

Add a NULL check for iomem resource in mailbox probe functions.
Signed-off-by: Fernando Guzman Lugo <lugo.fernando@gmail.com>
Signed-off-by: Suman Anna <s-anna@ti.com>

arch/arm/mach-omap1/mailbox.c

@@ -152,6 +152,9 @@ static int omap1_mbox_probe(struct platform_device *pdev)
 	list[0]->irq = platform_get_irq_byname(pdev, "dsp");
 
 	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!mem)
+		return -ENOENT;
+
 	mbox_base = ioremap(mem->start, resource_size(mem));
 	if (!mbox_base)
 		return -ENOMEM;

arch/arm/mach-omap2/mailbox.c

@@ -382,6 +382,9 @@ static int omap2_mbox_probe(struct platform_device *pdev)
 	}
 
 	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!mem)
+		return -ENOENT;
+
 	mbox_base = ioremap(mem->start, resource_size(mem));
 	if (!mbox_base)
 		return -ENOMEM;