A previous commit of mine used the target variable for two different uses
resulting in a lot more sstate being installed than is needed.
Fix the variable to use two different names and unbreak the setscene
behaviour.
(Bitbake rev: f975ca2cf728561bd6317ed8f76303598546113a)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>