dts/arm/st: Remove unneeded setting of #{address,size}-cells from RTC
dts/arm/st: Remove unneeded setting of #{address,size}-cells from RTC

The RTC node for some reason was setting #address-cells and #size-cells.
However it has no children so there isn't really any reason to do this.

Signed-off-by: Kumar Gala <a5e5248af4cd4f0ed8c515f61d40a6e2db46a66e@linaro.org>

ldts/zephyr,galak/zephyr,Vudentz/zephyr,punitvara/zephyr,nashif/zephyr,Vudentz/zephyr,ldts/zephyr,zephyrproject-rtos/zephyr,explora26/zephyr,galak/zephyr,kraj/zephyr,nashif/zephyr,punitvara/zephyr,kraj/zephyr,Vudentz/zephyr,punitvara/zephyr,explora26/zephyr,explora26/zephyr,GiulianoFranchetto/zephyr,GiulianoFranchetto/zephyr,kraj/zephyr,galak/zephyr,ldts/zephyr,kraj/zephyr,finikorg/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,ldts/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,punitvara/zephyr,nashif/zephyr,GiulianoFranchetto/zephyr,punitvara/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,finikorg/zephyr,Vudentz/zephyr,explora26/zephyr,nashif/zephyr,finikorg/zephyr,ldts/zephyr,Vudentz/zephyr,kraj/zephyr,galak/zephyr,explora26/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr