drivers: bbram: npcx: bypass npcx49nf errata rev1.5 No.2.30

This commit workarounds the BBRAM status register write issue in npcx4:
A write operation to the BKUP_STS register might disable write to all
the Battery-Backed RAM (BBRM). The workaround is to perform a fake read
from the BKUP_STS register after every write to this register.

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