ramips: enable fast-read for TL-MR3020 v3

The GigaDevices GD25Q64B found on the TL-MR3020 v3 supports the fast
read instruction. Add the required DT property in order to enable usage
of this property.

Signed-off-by: David Bauer <mail@david-bauer.net>

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

@@ -83,6 +83,7 @@
 		compatible = "jedec,spi-nor";
 		reg = <0>;
 		spi-max-frequency = <50000000>;
+		m25p,fast-read;
 
 		partitions {
 			compatible = "fixed-partitions";