lib: utils/irqchip: Add wrapper for T-HEAD PLIC delegation

The delegation bit is lost along with the rest of the PLIC state when
the CPU power domain in the Allwinner D1 is powered down, so the PLIC
needs to be re-delegated to S-mode during the hart resume path.

Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Samuel Holland <samuel@sholland.org>

lib/utils/irqchip/fdt_irqchip_plic.c

@@ -151,6 +151,13 @@ static void thead_plic_plat_init(struct plic_data *pd)
 	writel_relaxed(BIT(0), (char *)pd->addr + THEAD_PLIC_CTRL_REG);
 }
 
+void thead_plic_restore(void)
+{
+	struct plic_data *plic = plic_hartid2data[current_hartid()];
+
+	thead_plic_plat_init(plic);
+}
+
 static const struct fdt_match irqchip_plic_match[] = {
 	{ .compatible = "riscv,plic0" },
 	{ .compatible = "sifive,plic-1.0.0" },