openharmony-zephyr.conf: Introduce zephyr distro config

Add OpenHarmony wrapper for the Zephyr distro config.
This doesn't add any functionality on top of zephyr.conf
but rather aligns it with openharmony-linux distro naming
convention. DISTRO_VERSION is same as its Linux counterpart.

Signed-off-by: Zbigniew Bodek <zbigniew.bodek@huawei.com>