windcharger: fix ACTIVATED_KERNEL_NAME after failover

Change-Id: Id901f83a1a2667e5cca60c7799c3fccfca126409
diff --git a/board/atheros/board953x/extra.c b/board/atheros/board953x/extra.c
index 841b15e..a5befd8 100755
--- a/board/atheros/board953x/extra.c
+++ b/board/atheros/board953x/extra.c
@@ -49,6 +49,7 @@
 		newp = "kernel1";
 	}
 	setenv("ACTIVATED_KERNEL_NAME", newp);
+	saveenv();
 	printf("*** Warning *** failover: switched to %s\n", newp);
 }