meta-ohos: Add meta-ohos-core to the Zephyr's sample bblayers

meta-ohos-core contains DISTRO configurations that
may be used by Zephyr build. In the future some images
also may be added.

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

flavours/zephyr/bblayers.conf.sample

@@ -10,5 +10,6 @@ BBLAYERS ?= " \
   ##OEROOT##/../meta-openembedded/meta-oe \
   ##OEROOT##/../meta-openembedded/meta-python \
   ##OEROOT##/../meta-zephyr \
+  ##OEROOT##/../meta-ohos/meta-ohos-core \
   ##OEROOT##/../meta-ohos/meta-ohos-foundation \
   "