The frdm_kw41z can be used as a standalone board or as an arduino
shield. Zephyr already supports the standalone configuration, this
change introduces support the arduino shield configuration.
In the arduino configuration, the frdm_kw41z operates as a ble
controller over serial hci. It can be attached to another board, such as
the frdm_k64f or mimxrt1050_evk, which runs the ble host.
Signed-off-by: Maureen Helm <maureen.helm@nxp.com>