lib: utils/irqchip: Add FDT based driver for IMSIC

We add simple FDT irqchip driver for IMSIC so that generic platform
(and other FDT based platforms) can utilize common IMIC library.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>

lib/utils/irqchip/fdt_irqchip.c

@@ -12,9 +12,11 @@
 #include <sbi_utils/fdt/fdt_helper.h>
 #include <sbi_utils/irqchip/fdt_irqchip.h>
 
+extern struct fdt_irqchip fdt_irqchip_imsic;
 extern struct fdt_irqchip fdt_irqchip_plic;
 
 static struct fdt_irqchip *irqchip_drivers[] = {
+	&fdt_irqchip_imsic,
 	&fdt_irqchip_plic
 };