Bluetooth: Host: Move new `bt_data` functions to `data.c`

Move newly added `bt_data_get_len` and `bt_data_serialize` from `ead.c`
to `data.c`.

Also, removed unnecessary include of `zephyr/kernel.h`.

Signed-off-by: Théo Battrel <theo.battrel@nordicsemi.no>
2 files changed