package/setools: update the project location in the Kconfig help
setools is no longer hosted on https://github.com/TresysTechnology/setools/.
Updated the Kconfig help to point to its new home,
https://github.com/SELinuxProject/setools/.
Signed-off-by: Antoine Tenart <antoine.tenart@bootlin.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>