ARM: dts: da850-evm: fix read access to SPI flash

commit 43849785 upstream.

Read access to the SPI flash are broken on da850-evm, i.e. the data
read is not what is actually programmed on the flash.
According to the datasheet for the M25P64 part present on the da850-evm,
if the SPI frequency is higher than 20MHz then the READ command is not
usable anymore and only the FAST_READ command can be used to read data.

This commit specifies in the DTS that we should use FAST_READ command
instead of the READ command.
Tested-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Fabien Parent <fparent@baylibre.com>
[nsekhar@ti.com: subject line adjustment]
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

arch/arm/boot/dts/da850-evm.dts

@@ -59,6 +59,7 @@ flash: m25p80@0 {
 				#size-cells = <1>;
 				compatible = "m25p64";
 				spi-max-frequency = <30000000>;
+				m25p,fast-read;
 				reg = <0>;
 				partition@0 {
 					label = "U-Boot-SPL";