ARM: ux500: add spin_unlock(&master_lock).

Add the missing spin_unlock statement to unlock
master_lock when prcmu_gic_decouple() return TRUE
Signed-off-by: Nsteve zhan <zhanzhenbo@gmail.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

arch/arm/mach-ux500/cpuidle.c

@@ -40,8 +40,10 @@ static inline int ux500_enter_idle(struct cpuidle_device *dev,
 			goto wfi;
 
 		/* decouple the gic from the A9 cores */
-		if (prcmu_gic_decouple())
+		if (prcmu_gic_decouple()) {
+			spin_unlock(&master_lock);
 			goto out;
+		}
 
 		/* If an error occur, we will have to recouple the gic
 		 * manually */