Revert "Switch to toybox ls."

This reverts commit 981564094b07bb82d78667f317478a8a018a814b.

Change-Id: Ib84805d06a8ba281bc2a5d2f2b469f6f07d1769a
(cherry picked from commit 45d0f825c8d3c3b2dea18796ebb04071672ead0f)
diff --git a/Android.mk b/Android.mk
index b653ecf..fa54f05 100644
--- a/Android.mk
+++ b/Android.mk
@@ -215,7 +215,7 @@
 
 LOCAL_MODULE := toybox
 
-# dupes: dd df du mount renice
+# dupes: dd df du ls mount renice
 # useless?: freeramdisk fsfreeze install makedevs mkfifo nbd-client
 #           partprobe pivot_root pwdx rev rfkill switch_root tty vconfig
 # prefer BSD netcat instead?: nc netcat
@@ -268,7 +268,6 @@
     ln \
     logname \
     losetup \
-    ls \
     lsmod \
     lsusb \
     md5sum \