fix(core): dump cores on persistent location

Author: mittachaitu

docker/entrypoint-poolimage.sh

@@ -24,7 +24,7 @@ else
 	ulimit -c unlimited
 	## /var/openebs is mounted as persistent directory on
 	## host machine
-	cd /var/openebs || exit
+	cd /var/openebs/cstor-pool || exit
 	mkdir -p core
 	cd core