arm64: dts: amlogic: a4: add ao secure node

Add node for board info registers, which allows getting SoC family and
board revision.

For example, with MESON_GX_SOCINFO config enabled we can get the
following information for board with Amlogic A4 SoC:
soc soc0: Amlogic A4 (A113L2) Revision 40:b (1:1) Detected.

Signed-off-by: Xianwei Zhao <[e-mail]>
Reviewed-by: Neil Armstrong <[e-mail]>
Acked-by: Conor Dooley <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Neil Armstrong <[e-mail]>

arch/arm64/boot/dts/amlogic/amlogic-a4-common.dtsi

···
 				clock-names = "xtal", "pclk", "baud";
 				status = "disabled";
 			};
+
+			sec_ao: ao-secure@10220 {
+				compatible = "amlogic,a4-ao-secure",
+					     "amlogic,meson-gx-ao-secure",
+					     "syscon";
+				reg = <0x0 0x10220 0x0 0x140>;
+				amlogic,has-chip-id;
+			};
 		};
 	};
 };