ARM: dts: aspeed-g4: Add all flash chips

The FMC supports five chip selects, so describe the five possible flash
chips.

Reviewed-by: Andrew Jeffery <[e-mail]>
Signed-off-by: Joel Stanley <[e-mail]>

arch/arm/boot/dts/aspeed-g4.dtsi

···
 				compatible = "jedec,spi-nor";
 				status = "disabled";
 			};
+			flash@1 {
+				reg = < 1 >;
+				compatible = "jedec,spi-nor";
+				status = "disabled";
+			};
+			flash@2 {
+				reg = < 2 >;
+				compatible = "jedec,spi-nor";
+				status = "disabled";
+			};
+			flash@3 {
+				reg = < 3 >;
+				compatible = "jedec,spi-nor";
+				status = "disabled";
+			};
+			flash@4 {
+				reg = < 4 >;
+				compatible = "jedec,spi-nor";
+				status = "disabled";
+			};
 		};
 
 		spi: spi@1e630000 {