boards: arm: Enable arduino serial port on mimxrt685_evk

Configures flexcomm4 to operate in USART mode and enables the associated
peripheral clock and pinmuxes. This instance is attached to the Arduino
serial header pins and can be used for Bluetooth serial HCI with a
frdm_kw41z or other BLE controller shield.

Signed-off-by: Maureen Helm <maureen.helm@nxp.com>
5 files changed