Fix powerwash doesn't work in Acloud

Add powerwash command into Acloud help message.

Bug: 288022909
Test: acloud powerwash
Change-Id: I58419f0bd8f8170fd1d7dc9f0ff4534ba550ac25
diff --git a/public/acloud_main.py b/public/acloud_main.py
index 9893670..1b38fc3 100644
--- a/public/acloud_main.py
+++ b/public/acloud_main.py
@@ -152,6 +152,7 @@
         list_args.CMD_LIST,
         delete_args.CMD_DELETE,
         reconnect_args.CMD_RECONNECT,
+        powerwash_args.CMD_POWERWASH,
         pull_args.CMD_PULL,
         restart_args.CMD_RESTART,
         hostcleanup_args.CMD_HOSTCLEANUP]