MIPS: Loongson64: Increase NR_IRQS to 320

Modernized Loongson64 uses a hierarchical organization for interrupt
controllers (INTCs), all INTC nodes (not only leaf nodes) need some IRQ
numbers. This means 280 (i.e., NR_IRQS_LEGACY + NR_MIPS_CPU_IRQS + 256)
is not enough to represent all interrupts, so let's increase NR_IRQS to
320 (NR_IRQS_LEGACY + NR_MIPS_CPU_IRQS + NR_MAX_CHAINED_IRQS + 256).
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/include/asm/mach-loongson64/irq.h

@@ -7,7 +7,8 @@
 /* cpu core interrupt numbers */
 #define NR_IRQS_LEGACY		16
 #define NR_MIPS_CPU_IRQS	8
-#define NR_IRQS			(NR_IRQS_LEGACY + NR_MIPS_CPU_IRQS + 256)
+#define NR_MAX_CHAINED_IRQS	40 /* Chained IRQs means those not directly used by devices */
+#define NR_IRQS			(NR_IRQS_LEGACY + NR_MIPS_CPU_IRQS + NR_MAX_CHAINED_IRQS + 256)
 
 #define MIPS_CPU_IRQ_BASE 	NR_IRQS_LEGACY