Fixed Scale shader to only scale RGB.
Fixed Scale shader to only scale RGB.

Signed-off-by: Steven Lovegrove <39eb4d4ddd155112407f1df63652248131653153@gmail.com>

renzodenardi/Pangolin,GrimDerp/Pangolin,pinglin/Pangolin,randi120/Pangolin,janjachnik/Pangolin,stevenlovegrove/Pangolin,stevenlovegrove/Pangolin,pinglin/Pangolin,renzodenardi/Pangolin,contradict/Pangolin,arpg/Pangolin,wxdzju/Pangolin,stevenlovegrove/Pangolin,wxdzju/Pangolin,janjachnik/Pangolin,mp3guy/Pangolin,visigoth/Pangolin,arpg/Pangolin,tschmidt23/Pangolin,mp3guy/Pangolin,randi120/Pangolin,tschmidt23/Pangolin,mp3guy/Pangolin,tschmidt23/Pangolin,contradict/Pangolin,GrimDerp/Pangolin,visigoth/Pangolin