irqchip: add C-SKY SMP interrupt controller

The driver is for C-SKY SMP interrupt controller. It support 16
soft-irqs, 16 private-irqs, and 992 max external-irqs, a total of
1024 interrupts.

C-SKY CPU 807/810/860 SMP/non-SMP could use it.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>

drivers/irqchip/Kconfig

@@ -371,6 +371,15 @@ config QCOM_PDC
 	  Power Domain Controller driver to manage and configure wakeup
 	  IRQs for Qualcomm Technologies Inc (QTI) mobile chips.
 
+config CSKY_MPINTC
+	bool "C-SKY Multi Processor Interrupt Controller"
+	depends on CSKY
+	help
+	  Say yes here to enable C-SKY SMP interrupt controller driver used
+	  for C-SKY SMP system.
+	  In fact it's not mmio map in hw and it use ld/st to visit the
+	  controller's register inside CPU.
+
 endmenu
 
 config SIFIVE_PLIC