bcm63xx: periph_intc: fix warning

drivers/irqchip/irq-bcm6345-periph.c: In function 'bcm6345_periph_irq_handle':
drivers/irqchip/irq-bcm6345-periph.c:55:21: warning: 'block' may be used uninitialized in this function [-Wmaybe-uninitialized]
  struct intc_block *block;
                     ^~~~~

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
(cherry picked from commit f2f2cf07a61e9c170ab8d65e1e054f0131a84e2a)

target/linux/brcm63xx/patches-4.14/324-irqchip-bcm6345-periph-fix-block-uninitialized.patch

@@ -0,0 +1,20 @@
+--- a/drivers/irqchip/irq-bcm6345-periph.c
++++ b/drivers/irqchip/irq-bcm6345-periph.c
+@@ -52,7 +52,7 @@ static void bcm6345_periph_irq_handle(st
+ {
+ 	struct intc_data *data = irq_desc_get_handler_data(desc);
+ 	struct irq_chip *chip = irq_desc_get_chip(desc);
+-	struct intc_block *block;
++	struct intc_block *block = NULL;
+ 	unsigned int irq = irq_desc_get_irq(desc);
+ 	unsigned int idx;
+ 
+@@ -62,7 +62,7 @@ static void bcm6345_periph_irq_handle(st
+ 		if (irq == data->block[idx].parent_irq)
+ 			block = &data->block[idx];
+ 
+-	for (idx = 0; idx < data->num_words; idx++) {
++	for (idx = 0; block && idx < data->num_words; idx++) {
+ 		int base = idx * IRQS_PER_WORD;
+ 		unsigned long pending;
+ 		int hw_irq;