ARM: OMAP3+: PRM: fix of_irq_get() result check

of_irq_get() may return 0 as well as a nagative error number on failure
(and never on success), however omap3xxx_prm_late_init() regards 0 as a
valid IRQ -- fix this.

Fixes: 1e03779 ("ARM: OMAP3+: PRM: register interrupt information from DT")
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mach-omap2/prm3xxx.c

@@ -706,7 +706,7 @@ static int omap3xxx_prm_late_init(void)
 	np = of_find_matching_node(NULL, omap3_prm_dt_match_table);
 	if (np) {
 		irq_num = of_irq_get(np, 0);
-		if (irq_num >= 0)
+		if (irq_num > 0)
 			omap3_prcm_irq_setup.irq = irq_num;
 	}