Disable UART HWFC
Disable UART HWFC

For mbed Online Compiler because the VBLUNO51 use nrf51822 target

Signed-off-by: iotvietmember <64fcad58a287264cd3695b53aa5ee0c110ddcd62@gmail.com>

sg-/DAPLink,google/DAPLink-port,sg-/DAPLink,google/DAPLink-port,google/DAPLink-port,sg-/DAPLink,google/DAPLink-port