In added mode flash operation are performed in timeslice
(in radio idle time).
Kconfig for mode enabling CONFIG_SOC_FLASH_NRF5_RADIO_SYNC.
Erase and write API implementations were rewritten and preserved against
concurrent execution.
Signed-off-by: Andrzej Puzdrowski <andrzej.puzdrowski@nordicsemi.no>
Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>