ARM: dts: BCM5301X: Drop "clock-names" from the SPI node

There is no such property in the SPI controller binding documentation.
Also Linux driver doesn't look for it.

This fixes:
arch/arm/boot/dts/bcm4708-asus-rt-ac56u.dtb: spi@18029200: Unevaluated properties are not allowed ('clock-names' was unexpected)
        From schema: Documentation/devicetree/bindings/spi/brcm,spi-bcm-qspi.yaml
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Link: https://lore.kernel.org/r/20230503122830.3200-1-zajec5@gmail.comSigned-off-by: Florian Fainelli <f.fainelli@gmail.com>

arch/arm/boot/dts/bcm5301x.dtsi

@@ -335,7 +335,6 @@ spi@18029200 {
 				  "spi_lr_session_done",
 				  "spi_lr_overread";
 		clocks = <&iprocmed>;
-		clock-names = "iprocmed";
 		num-cs = <2>;
 		#address-cells = <1>;
 		#size-cells = <0>;