ARM: ux500: fix prcmu_is_cpu_in_wfi() calculation

This function clearly never worked and always returns true,
as pointed out by gcc-7:

arch/arm/mach-ux500/pm.c: In function 'prcmu_is_cpu_in_wfi':
arch/arm/mach-ux500/pm.c:137:212: error: ?:
using integer constants in boolean context, the expression
will always evaluate to 'true' [-Werror=int-in-bool-context]

With the added braces, the condition actually makes sense.

Fixes: 34fe6f10 ("mfd : Check if the other db8500 core is in WFI")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

arch/arm/mach-ux500/pm.c

@@ -134,8 +134,8 @@ bool prcmu_pending_irq(void)
  */
 bool prcmu_is_cpu_in_wfi(int cpu)
 {
-	return readl(PRCM_ARM_WFI_STANDBY) & cpu ? PRCM_ARM_WFI_STANDBY_WFI1 :
-		     PRCM_ARM_WFI_STANDBY_WFI0;
+	return readl(PRCM_ARM_WFI_STANDBY) &
+		(cpu ? PRCM_ARM_WFI_STANDBY_WFI1 : PRCM_ARM_WFI_STANDBY_WFI0);
 }
 
 /*