/sdcard: do not bind mount twice

Change-Id: I1757eb8732a01a728392c3499ac3300c81522806
(cherry picked from commit 36cb2ad28ed99f18538921e5152627abbde08298)
diff --git a/partition.cpp b/partition.cpp
index 1fdd011..0a858a8 100755
--- a/partition.cpp
+++ b/partition.cpp
@@ -1594,7 +1594,7 @@
 	if (Removable)
 		Update_Size(Display_Error);
 
-	if (!Symlink_Mount_Point.empty()) {
+	if (!Symlink_Mount_Point.empty() && Symlink_Mount_Point != "/sdcard") {
 		if (!Bind_Mount(false))
 			return false;
 	}