[hwsku-init] Introduce mechanism to run HWSKU specific initialization code (#2072)

When there is HWSKU specific initialization needs to be performed, please
add hwsku-init script under device folder, it will be invoked by swss
before any subsequent initializations.

Signed-off-by: Ying Xie <[email protected]>

Author: yxieca

dockers/docker-orchagent/start.sh

@@ -6,6 +6,11 @@ sonic-cfggen -d -t /usr/share/sonic/templates/switch.json.j2 > /etc/swss/config.
 sonic-cfggen -d -t /usr/share/sonic/templates/ipinip.json.j2 > /etc/swss/config.d/ipinip.json
 sonic-cfggen -d -t /usr/share/sonic/templates/ports.json.j2 > /etc/swss/config.d/ports.json
 
+# Executed HWSKU specific initialization tasks.
+if [ -x /usr/share/sonic/hwsku/hwsku-init ]; then
+    /usr/share/sonic/hwsku/hwsku-init
+fi
+
 export platform=`sonic-cfggen -H -v DEVICE_METADATA.localhost.platform`
 
 rm -f /var/run/rsyslogd.pid