ramips: increase SPI frequency for TL-MR3020 v3

The GigaDevices GD25Q64B supports higher SPI clocks than 10 MHz. While
100 MHz do not work reliably, 50 MHz works without issues.

Signed-off-by: David Bauer <[email protected]>

target/linux/ramips/dts/mt7628an_tplink_tl-mr3020-v3.dts

@@ -82,7 +82,7 @@
 	flash@0 {
 		compatible = "jedec,spi-nor";
 		reg = <0>;
-		spi-max-frequency = <10000000>;
+		spi-max-frequency = <50000000>;
 
 		partitions {
 			compatible = "fixed-partitions";