dts: npcx: remove unnecessary sub-power state for npcx4

NPCX9 and former chips defines two kinds of sub-power-states to support:
1. Standard wake-up time: if the chip needs to stay in the deep sleep
   state more than 200 ms.
2. Instant wake-up time: if the chip needs to stay in the deep sleep
   state less than 200 ms.

As NPCX4 can stay in the deep sleep state at more than 200 ms with the
instant wake-up capability, we can define only one sub-power state.

Signed-off-by: Jun Lin <CHLin56@nuvoton.com>