arm: omap1: mbox: make variables static

Make some variables static to get rid of the following warnings:

arch/arm/mach-omap1/mailbox.c:136:18: warning: symbol 'mbox_dsp_info' was not declared. Should it be static?
arch/arm/mach-omap1/mailbox.c:142:18: warning: symbol 'omap1_mboxes' was not declared. Should it be static?

Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mach-omap1/mailbox.c

@@ -133,13 +133,13 @@ static struct omap_mbox1_priv omap1_mbox_dsp_priv = {
 	},
 };
 
-struct omap_mbox mbox_dsp_info = {
+static struct omap_mbox mbox_dsp_info = {
 	.name	= "dsp",
 	.ops	= &omap1_mbox_ops,
 	.priv	= &omap1_mbox_dsp_priv,
 };
 
-struct omap_mbox *omap1_mboxes[] = { &mbox_dsp_info, NULL };
+static struct omap_mbox *omap1_mboxes[] = { &mbox_dsp_info, NULL };
 
 static int __devinit omap1_mbox_probe(struct platform_device *pdev)
 {