arm64: dts: meson: remove clock-frequency from rtc

'clock-frequency' is not part of the DT binding and not supported by the
Linux driver.
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20221024165549.74574-6-sebastian.reichel@collabora.comSigned-off-by: Neil Armstrong <neil.armstrong@linaro.org>

arch/arm64/boot/dts/amlogic/meson-gxl-s905x-khadas-vim.dts

@@ -140,7 +140,6 @@ rtc: rtc@51 {
 		compatible = "haoyu,hym8563";
 		reg = <0x51>;
 		#clock-cells = <0>;
-		clock-frequency = <32768>;
 		clock-output-names = "xin32k";
 	};
 };

arch/arm64/boot/dts/amlogic/meson-gxm-khadas-vim2.dts

@@ -270,7 +270,6 @@ rtc: rtc@51 {
 		compatible = "haoyu,hym8563";
 		reg = <0x51>;
 		#clock-cells = <0>;
-		clock-frequency = <32768>;
 		clock-output-names = "xin32k";
 	};
 };

arch/arm64/boot/dts/amlogic/meson-gxm-minix-neo-u9h.dts

@@ -89,7 +89,6 @@ rtc: rtc@51 {
 		compatible = "haoyu,hym8563";
 		reg = <0x51>;
 		#clock-cells = <0>;
-		clock-frequency = <32768>;
 		clock-output-names = "xin32k";
 		wakeup-source;
 	};