MIPS: Loongson 3: Add IRQ init and dispatch support

IRQ routing path of Loongson-3:
Devices(most) --> I8259 --> HT Controller --> IRQ Routing Table --> CPU
                                                  ^
                                                  |
Device(legacy devices such as UART) --> Bonito ---|

IRQ Routing Table route 32 INTs to CPU's INT0~INT3(IP2~IP5 of CP0), 32
INTs include 16 HT INTs(mostly), 4 PCI INTs, 1 LPC INT, etc. IP6 is used
for IPI and IP7 is used for internal MIPS timer. LOONGSON_INT_ROUTER_*
are IRQ Routing Table registers.

I8259 IRQs are 1:1 mapped to HT1 INTs. LOONGSON_HT1_* are configuration
registers of HT1 controller.

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Hongliang Tao <taohl@lemote.com>
Signed-off-by: Hua Yan <yanh@lemote.com>
Tested-by: Alex Smith <alex.smith@imgtec.com>
Reviewed-by: Alex Smith <alex.smith@imgtec.com>
Cc: John Crispin <john@phrozen.org>
Cc: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: linux-mips@linux-mips.org
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Zhangjin Wu <wuzhangjin@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/6634
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/loongson/Makefile b/arch/mips/loongson/Makefile
index 0dc0055..7429994 100644
--- a/arch/mips/loongson/Makefile
+++ b/arch/mips/loongson/Makefile
@@ -15,3 +15,9 @@
 #
 
 obj-$(CONFIG_LEMOTE_MACH2F)  += lemote-2f/
+
+#
+# All Loongson-3 family machines
+#
+
+obj-$(CONFIG_CPU_LOONGSON3)  += loongson-3/