MIPS: ralink: add PCI IRQ handling

The Ralink IRQ code was not handling the PCI IRQ yet. Add this functionaility
to make PCI work on rt3883.

Signed-off-by: John Crispin <blogic@openwrt.org>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/5165/

arch/mips/ralink/irq.c

@@ -31,6 +31,7 @@
 #define INTC_INT_GLOBAL		BIT(31)
 
 #define RALINK_CPU_IRQ_INTC	(MIPS_CPU_IRQ_BASE + 2)
+#define RALINK_CPU_IRQ_PCI	(MIPS_CPU_IRQ_BASE + 4)
 #define RALINK_CPU_IRQ_FE	(MIPS_CPU_IRQ_BASE + 5)
 #define RALINK_CPU_IRQ_WIFI	(MIPS_CPU_IRQ_BASE + 6)
 #define RALINK_CPU_IRQ_COUNTER	(MIPS_CPU_IRQ_BASE + 7)
@@ -104,6 +105,9 @@ asmlinkage void plat_irq_dispatch(void)
 	else if (pending & STATUSF_IP6)
 		do_IRQ(RALINK_CPU_IRQ_WIFI);
 
+	else if (pending & STATUSF_IP4)
+		do_IRQ(RALINK_CPU_IRQ_PCI);
+
 	else if (pending & STATUSF_IP2)
 		do_IRQ(RALINK_CPU_IRQ_INTC);