cns3xxx: fix GPIO controller interrupt enable

The cns3xxx interrupt controller uses a single register and as such
the 'mask' reg/functions must be used as opposed to the 'enable'/'disable'
reg/functions.

This fixes an issue that occurs if more than one GPIO on a specific controller
(there is GPIOA and GPIOB each having 32 GPIO's) uses interrupts. When one
would get enabled all others would be disabled prior to this patch.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Acked-by: Koen Vandeputte <koen.vandeputte@ncentric.com>

target/linux/cns3xxx/files/arch/arm/mach-cns3xxx/gpio.c

@@ -273,10 +273,10 @@ void __init cns3xxx_gpio_init(int gpio_base, int ngpio,
 	ct = gc->chip_types;
 	ct->type = IRQ_TYPE_EDGE_FALLING;
 	ct->regs.ack = GPIO_INTERRUPT_CLEAR;
-	ct->regs.enable = GPIO_INTERRUPT_ENABLE;
 	ct->chip.irq_ack = irq_gc_ack_set_bit;
-	ct->chip.irq_enable = irq_gc_unmask_enable_reg;
-	ct->chip.irq_disable = irq_gc_mask_disable_reg;
+	ct->regs.mask = GPIO_INTERRUPT_ENABLE;
+	ct->chip.irq_enable = irq_gc_mask_set_bit;
+	ct->chip.irq_disable = irq_gc_mask_clr_bit;
 	ct->chip.irq_set_type = cns3xxx_gpio_irq_set_type;
 	ct->handler = handle_edge_irq;