dt-bindings: rtc: pcf85063: remove quartz-load-femtofarads restriction for nxp,pcf85063

dt-bindings: rtc: pcf85063: remove quartz-load-femtofarads restriction for nxp,pcf85063

Original TXT binding doc have not limitition about quartz-load-femtofarads,
which only allow 7000 for nxp,pcf85063.

So remove it to fix below CHECK_DTBS warnings:
arch/arm/boot/dts/nxp/imx/imx6dl-skov-revc-lt2.dtb: rtc@51 (nxp,pcf85063): quartz-load-femtofarads:0: 7000 was expected
        from schema $id: http://devicetree.org/schemas/rtc/nxp,pcf85063.yaml#

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250903191128.439164-1-Frank.Li@nxp.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>