zephyr: ITE flash remove deprecated macro
zephyr: ITE flash remove deprecated macro

Zephyr upstream deprecated DT_CHOSEN_ZEPHYR_FLASH_CONTROLLER_LABEL and
indicates that DT_LABEL(DT_CHOSEN(zephyr_flash_controller)) should be
used instead.

https://github.com/zephyrproject-rtos/zephyr/blob/69f5edfa45c548751f2886dfdf0e67e57c1f9a05/include/devicetree/zephyr.h#L49

BUG=none
BRANCH=none
TEST=zmake testall

Signed-off-by: Keith Short <f6d578f97033c25f1206cb57d52f358974c82954@chromium.org>
Change-Id: Id38f056ae183e7e43791cf6f9aae3e605d8b7916
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3566098
Reviewed-by: Jack Rosenthal <d3f605bef1867f59845d4ce6e4f83b8dc9e4e0ae@chromium.org>
Feels: Jack Rosenthal <d3f605bef1867f59845d4ce6e4f83b8dc9e4e0ae@chromium.org>
Feels: Paul Fagerburg <d8c44b60afb21c60f56d931aa690ca1cf34910c8@chromium.org>

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