This CL configures the UART wake-up event triggered from a falling edge
(START condition) on CR_SIN pin. It also includes:
1. Introduce wui_maps property in yaml file to present relationship
between Wake-Up Input (WUI) and UART device.
2. Implement wake-up mechanism by MIWU api functions.
Signed-off-by: Mulin Chao <MLChao@nuvoton.com>