ARM: picoxcell: fix missing interrupt-parent properties

dtc points out that the interrupts for some devices are not parsable:

picoxcell-pc3x2.dtsi:45.19-49.5: Warning (interrupts_property): /paxi/gem@30000: Missing interrupt-parent
picoxcell-pc3x2.dtsi:51.21-55.5: Warning (interrupts_property): /paxi/dmac@40000: Missing interrupt-parent
picoxcell-pc3x2.dtsi:57.21-61.5: Warning (interrupts_property): /paxi/dmac@50000: Missing interrupt-parent
picoxcell-pc3x2.dtsi:233.21-237.5: Warning (interrupts_property): /rwid-axi/axi2pico@c0000000: Missing interrupt-parent

There are two VIC instances, so it's not clear which one needs to be
used. I found the BSP sources that reference VIC0, so use that:

https://github.com/r1mikey/meta-picoxcell/blob/master/recipes-kernel/linux/linux-picochip-3.0/0001-picoxcell-support-for-Picochip-picoXcell-SoC.patchAcked-by: Jamie Iles <jamie@jamieiles.com>
Link: https://lore.kernel.org/r/20201230152010.3914962-1-arnd@kernel.org'
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/boot/dts/picoxcell-pc3x2.dtsi

@@ -45,18 +45,21 @@ paxi {
 		emac: gem@30000 {
 			compatible = "cadence,gem";
 			reg = <0x30000 0x10000>;
+			interrupt-parent = <&vic0>;
 			interrupts = <31>;
 		};
 
 		dmac1: dmac@40000 {
 			compatible = "snps,dw-dmac";
 			reg = <0x40000 0x10000>;
+			interrupt-parent = <&vic0>;
 			interrupts = <25>;
 		};
 
 		dmac2: dmac@50000 {
 			compatible = "snps,dw-dmac";
 			reg = <0x50000 0x10000>;
+			interrupt-parent = <&vic0>;
 			interrupts = <26>;
 		};
 
@@ -233,6 +236,7 @@ ebi@50000000 {
 		axi2pico@c0000000 {
 			compatible = "picochip,axi2pico-pc3x2";
 			reg = <0xc0000000 0x10000>;
+			interrupt-parent = <&vic0>;
 			interrupts = <13 14 15 16 17 18 19 20 21>;
 		};
 	};