irqchip/aspeed-vic: Add AST2500 compatible string

In addition to introducing the new compatible string the bindings
description is reworked to be more generic.
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NAndrew Jeffery <andrew@aj.id.au>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

Documentation/devicetree/bindings/interrupt-controller/aspeed,ast2400-vic.txt

 Aspeed Vectored Interrupt Controller
 
-These bindings are for the Aspeed AST2400 interrupt controller register layout.
-The SoC has an legacy register layout, but this driver does not support that
-mode of operation.
+These bindings are for the Aspeed interrupt controller. The AST2400 and
+AST2500 SoC families include a legacy register layout before a re-designed
+layout, but the bindings do not prescribe the use of one or the other.
 
 Required properties:
 
-- compatible : should be "aspeed,ast2400-vic".
+- compatible : "aspeed,ast2400-vic"
+               "aspeed,ast2500-vic"
 
 - interrupt-controller : Identifies the node as an interrupt controller
 - #interrupt-cells : Specifies the number of cells needed to encode an

drivers/irqchip/irq-aspeed-vic.c

@@ -227,4 +227,5 @@ static int __init avic_of_init(struct device_node *node,
 	return 0;
 }
 
-IRQCHIP_DECLARE(aspeed_new_vic, "aspeed,ast2400-vic", avic_of_init);
+IRQCHIP_DECLARE(ast2400_vic, "aspeed,ast2400-vic", avic_of_init);
+IRQCHIP_DECLARE(ast2500_vic, "aspeed,ast2500-vic", avic_of_init);