Properly set mtp enable variable if disabled during boot

Change-Id: Iedf08419a1fd46908e5b9186a769a0497ce62ca8
diff --git a/twrp.cpp b/twrp.cpp
index 870a732..d9a5ab1 100644
--- a/twrp.cpp
+++ b/twrp.cpp
@@ -312,6 +312,7 @@
 		property_set("mtp.crash_check", "0");
 	} else {
 		gui_print_color("warning", "MTP Crashed, not starting MTP on boot.\n");
+		DataManager::SetValue("tw_mtp_enabled", 0);
 	}
 #endif