Don't prompt to install Superuser is SuperSu is already present:
	Also do not try to repair SuperSu in anyway as it will
	always prompt to repair root even when it already works
	and doing so does not actually stop the prompt either.

Change-Id: I6651eaebabfe829250fe42c6693e61a5cae871d6
Signed-off-by: Nathan Bass <sblood86@gmail.com>