zephyr: flash: npcx: Refactor flash_get_status()
zephyr: flash: npcx: Refactor flash_get_status()

NPCX internal flash status register 1/2 are always read at the same
time. This CL merges flash_get_status1() and flash_get_status2() into
one function. This improves the performance by eliminating duplicate
mutex function call operations.
This change aligns with the change in the CL:3247742 of ECOS.

BUG=none
BRANCH=none
TEST=write status1/2 registers with different values, read them back
with console command "flashchip"

Signed-off-by: Jun Lin <4865d89268068846db8afe2dcacc793288c792a0@nuvoton.com>
Change-Id: I414424401df22eaa577d3e5238cdeae06eb5e61d
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3268036
Tested-by: CH Lin <49997681dc186e71092740314bf6c6feeca6e227@nuvoton.com>
Reviewed-by: Keith Short <f6d578f97033c25f1206cb57d52f358974c82954@chromium.org>
Reviewed-by: Jack Rosenthal <d3f605bef1867f59845d4ce6e4f83b8dc9e4e0ae@chromium.org>
Commit-Queue: Keith Short <f6d578f97033c25f1206cb57d52f358974c82954@chromium.org>

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