make tool-siwiflasher optional

Signed-off-by: Ajay Bhargav <[email protected]>

Author: ajaybhargav

platform.json

@@ -33,6 +33,7 @@
 		},
 		"tool-siwiflasher": {
 			"type": "uploader",
+			"optional": true,
 			"version": "~1.0.0"
 		}
 	}