npcx: espi: move DT nodes to specific files which support them

Since VWGPSM (Virtual Wire GPIO Target-to-Controller) registers are
introduced in npcx9 and later series, the CL moves the related DT nodes
from npcx-espi-vws-map.dtsi (Used for all npcx series) to the specific
dtsi files for npcx9 and npcx4 series.

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