irqchip/sifive-plic: Fix T-HEAD PLIC edge trigger handling

The T-HEAD PLIC ignores additional edges seen while an edge-triggered
interrupt is being handled. Because of this behavior, the driver needs
to complete edge-triggered interrupts in the .irq_ack callback before
handling them, instead of in the .irq_eoi callback afterward. Otherwise,
it could miss some interrupts.
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220630100241.35233-5-samuel@sholland.org

drivers/irqchip/irq-sifive-plic.c

@@ -474,7 +474,6 @@ static int __init plic_init(struct device_node *node,
 
 IRQCHIP_DECLARE(sifive_plic, "sifive,plic-1.0.0", plic_init);
 IRQCHIP_DECLARE(riscv_plic0, "riscv,plic0", plic_init); /* for legacy systems */
-IRQCHIP_DECLARE(thead_c900_plic, "thead,c900-plic", plic_init); /* for firmware driver */
 
 static int __init plic_edge_init(struct device_node *node,
 				 struct device_node *parent)
@@ -483,3 +482,4 @@ static int __init plic_edge_init(struct device_node *node,
 }
 
 IRQCHIP_DECLARE(andestech_nceplic100, "andestech,nceplic100", plic_edge_init);
+IRQCHIP_DECLARE(thead_c900_plic, "thead,c900-plic", plic_edge_init);