ARM: dts: aspeed-g4: Set spi-max-frequency for all flashes

Set "spi-max-frequency" to 50 MHz for all the flashes under the FMC
controller to ensure the clock frequency is calculated correctly.
Suggested-by: NCédric Le Goater <clg@kaod.org>
Tested-by: NJae Hyun Yoo <quic_jaehyoo@quicinc.com>
Signed-off-by: NTao Ren <rentao.bupt@gmail.com>
Signed-off-by: NCédric Le Goater <clg@kaod.org>
Link: https://lore.kernel.org/r/20220509175616.1089346-11-clg@kaod.orgSigned-off-by: NJoel Stanley <joel@jms.id.au>

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

@@ -72,24 +72,28 @@
 				reg = < 1 >;
 				compatible = "jedec,spi-nor";
 				spi-rx-bus-width = <2>;
+				spi-max-frequency = <50000000>;
 				status = "disabled";
 			};
 			flash@2 {
 				reg = < 2 >;
 				compatible = "jedec,spi-nor";
 				spi-rx-bus-width = <2>;
+				spi-max-frequency = <50000000>;
 				status = "disabled";
 			};
 			flash@3 {
 				reg = < 3 >;
 				compatible = "jedec,spi-nor";
 				spi-rx-bus-width = <2>;
+				spi-max-frequency = <50000000>;
 				status = "disabled";
 			};
 			flash@4 {
 				reg = < 4 >;
 				compatible = "jedec,spi-nor";
 				spi-rx-bus-width = <2>;
+				spi-max-frequency = <50000000>;
 				status = "disabled";
 			};
 		};