NR UE FAPI: provide ntn_config as part of phy_config.config_req instead of a dedicated scheduled_response dl_config PDU

We need the ntn_config when reconfiguring the PHY layer for a new initial sync,
e.g. for calculating the DL Doppler frequency.

As a dedicated scheduled_response dl_config PDU it reaches the PHY layer too late,
as part of the phy_config.config_req it reaches the PHY layer in time with the
other configuration values.