bluetooth: controller: replace SOC_NRF52840 in ifdef blocks for Coded

We have introduced option HAS_HW_NRF_RADIO_BLE_CODED, which
reflects that an nRF SoC has a Radio with LE Coded PHY
capabilities. We now modify all #ifdef expressions for
Coded PHY in the nRF controller port, removing SOC_NRF52840
and adding this new option instead. This allows to build
an nRF controller with Coded PHY support for SOCs other
than nRF52840.

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>