driver: espi: add more KBC 8042 support in npcx series.

This CL added more additional details for KBC (Keyboard and Mouse
Controller) bus in espi_event structure. It helps the application to
handle different 8042 events in the callback function.

The format of event data for KBC 8042 protocol is:
[23:16] - 8042 event type: 1: Input buf full, 2: Output buf empty.
[15:8]  - 8042 data: 8-bit 8042 data.
[0:7]   - 8042 protocol type: 0: data type, 1: command type.

Signed-off-by: Mulin Chao <mlchao@nuvoton.com>