overlay: Accept multiple targets for add and remove subcommands

Make operating on overlays less tedious

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: I29897c85adec7987e0302ee17802280c3ab591c0
diff --git a/overlay/overlay b/overlay/overlay
index e4dbc16..8c3ac99 100755
--- a/overlay/overlay
+++ b/overlay/overlay
@@ -54,10 +54,16 @@
 
 case $subcmd in
     add)
-        overlay_add $1
+        for target in "$@"
+        do
+            overlay_add "$target"
+        done
         ;;
     remove)
-        overlay_remove $1
+        for target in "$@"
+        do
+            overlay_remove "$target"
+        done
         ;;
     -h|--help|*)
         cat $0