irqchip/gicv3: Handle loop timeout proper

The timeout loop terminates when the loop count is zero, but the decrement
of the count variable is post check. So count is -1 when we check for the
timeout and therefor the error message is supressed.

Change it to predecrement, so the error message is emitted.

[ tglx: Massaged changelog ] 

Fixes: a2c2251 ("irqchip: gic-v3: Refactor gic_enable_redist to support both enabling and disabling")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: kernel-janitors@vger.kernel.org
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20161014072534.GA15168@mwanda
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

drivers/irqchip/irq-gic-v3.c

@@ -153,7 +153,7 @@ static void gic_enable_redist(bool enable)
 			return;	/* No PM support in this redistributor */
 	}
 
-	while (count--) {
+	while (--count) {
 		val = readl_relaxed(rbase + GICR_WAKER);
 		if (enable ^ (bool)(val & GICR_WAKER_ChildrenAsleep))
 			break;