zephyr: cleanup the structure member type
zephyr: cleanup the structure member type

Declare the member type to match the kscan_it8xxx2_regs, so
we needn't to transform the type every time in function for
the local structure.

BUG=none
BRANCH=none
TEST=on board krabby, console cmd "ksstate on",
     1.press multi-key at a time:
     [1811.881622 KB state: -- -- -- -- -- -- 12 -- -- -- -- -- --]
     [1811.933868 KB state: -- -- -- -- -- 10 12 -- -- -- -- -- --]
     [1811.981567 KB state: -- -- -- -- -- 10 10 -- -- -- -- -- --]
     2.press a key at a time:
       check all keyboard key bit field triggered

Signed-off-by: Ruibin Chang <6748d95250dd3d29f04d200035d5434f3b7820ef@ite.com.tw>
Change-Id: Id9cfdb3ad2626721a615da46a2b28fdb8962ef3e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3359109
Reviewed-by: Denis Brockus <6b21e8190fb5e373363fb95271367073a16474ef@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec