arch: arm: nrf: modification of config parameter: SOC_SERIES_NRF52X

Configuration parameter SOC_SERIES_NRF52X is common for all NRF5X SoCs.
Due to that it cannot select: CPU_HAS_FPU because not all Nordic
microcontrollers supports that. Selection of this parameter was moved
to configuration of each SoC in Kconfig.soc file.

Signed-off-by: Jakub Rzeszutko <jakub.rzeszutko@nordicsemi.no>