drivers: ieee802154: nrf: limit number of serialized calls

For serialized nRF IEEE 802.15.4 Driver host, avoid using
`nrf_802154_csl_writer_anchor_time_set` too often by caching the CSL
RX time and period and using them to detect any shift on the periodic
pattern.

This improves power consumption by limiting the number of serialized calls.

Signed-off-by: Eduardo Montoya <eduardo.montoya@nordicsemi.no>