oniro-zephyr-blueprint-gateway.conf: Add Gateway specific Zephyr distro

The mesh node application for the Gateway blueprint needs its own
blueprint distro as well.

Signed-off-by: Stefan Schmidt <stefan.schmidt@huawei.com>

meta-oniro-blueprints/conf/distro/oniro-zephyr-blueprint-gateway.conf

+# SPDX-FileCopyrightText: Huawei Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+# Distro configuration for the gateway blueprint
+
+require conf/distro/oniro-zephyr.conf
+
+DISTRO = "oniro-zephyr-blueprint-gateway"
+DISTRO_NAME = "Oniro Project Gateway Blueprint Zephyr Distro"
+
+# With our layer setup we would add any bbappend found from our
+# layers.conf. This means blueprint-specific appends would leak
+# into the package in our main distribution. To avoid this we
+# mask out the blueprint layers in the main distro and unmask
+# them only the blueprint distributions.
+BBMASK = ""