dts: npcx: replace series-prefix 'npcx7-' with famliy-prefix 'npcx-'

This CL replaces series-prefix "npcx7-" with family-"npcx-" for npcx dts
nodes such as 'espi-vws-map' and 'miwus-int-map'. Since we plan to
introduce the npcx9 and later series, adding a new node such as
npcx9-espi-vws-map for each series is more complicated and not
necessary.

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