Modify NFC to work with SDK 15.3

As usual, Nordic have completely refactored part of their SDK. While we can patch 15.2, 15.3 lacks the old 'hal_nfc_*' functions.

It doesn't look too bad to modify though. Andreas says:

Looking at targets/nrf5x/bluetooth.c we just need to rewire the calls from the
old api to the new one

- hal_nfc_setup -> nrfx_nfct_init
- hal_nfc_start -> nrfx_nfct_enable
- hal_nfc_parameter_set -> nrfx_nfct_parameter_set
- hal_nfc_parameter_get -> nrfx_nfct_nfcid1_default_bytes_get
- hal_nfc_send -> nrfx_nfct_tx
- hal_nfc_send_rsp -> nrfx_nfct_tx (assiming frame size is in bits)
- hal_nfc_stop -> nrfx_nfct_disable
- hal_nfc_done -> nrfx_nfct_uninit (not sure if this one is needed)

Start in targets/nrf5x/bluetooth.c and compare the listed hal_nfc_* calls with their nrfx_nfct equivalents in Nordic SDK 15.3. Check whether the frame size for nrfx_nfct_tx is in bits and whether nrfx_nfct_uninit is needed. Done means NFC builds and operates with SDK 15.3 using the replacement API.

Written by the indexing model from the issue text.