soc: npcx: Move ecst to npcx common folder

NPCX series ROM code changes the chip basic setting by firmware binary
header for loading the firmware from flash to RAM. Add the following to
improve the ec firmware header setting:

- Move the ECST which generates the firmware binary header to NPCX
common folder. All the following NPCX series chips can use this.
- Add ecst setting option in Kconfig.

Signed-off-by: Yuval Peress <peress@chromium.org>
Signed-off-by: Wealian Liao <WHLIAO@nuvoton.com>