Update SuperSU to 2.40

The SuperSU install process is getting rather complicated, so we
will modify the install script slightly and use it to install
all the things and stop trying to check to see if root permissions
have been lost like we used to do.

Change-Id: Ibdb64c909d2bd16e12bb35b4f31f572cc29add47
diff --git a/prebuilt/install-recovery.sh b/prebuilt/install-recovery.sh
old mode 100755
new mode 100644
index 7c65d0e..f62cf0b
--- a/prebuilt/install-recovery.sh
+++ b/prebuilt/install-recovery.sh
@@ -10,7 +10,7 @@
 
 /system/xbin/daemonsu --auto-daemon &
 
-# Some apps like to run stuff from this script as well, that will
+# Some apps like to run stuff from this script as well, that will 
 # obviously break root - in your code, just search this file
 # for "install-recovery-2.sh", and if present, write there instead.