Change add + shift syntax for arm assembly.
Change add + shift syntax for arm assembly.

Short syntax is not supported by all compilers.
Review URL: http://webrtc-codereview.appspot.com/265001
alfahim/libyuv,bingerZhang/libyuv,ganzhijie/libyuv,uditkumawat/libyuv,StopProducing/libyuv,dexcz/libyuv,StopProducing/libyuv,ganzhijie/libyuv,skufog/libyuv,Vairn/libyuv,RockySteveJobs/libyuv,VladDrake/libyuv,chucvv/libyuv,uraran/libyuv,dexcz/libyuv,syoshimu/libyuv,gigakuma/libyuv,yzhikan/libyuv,chucvv/libyuv,hyper123/libyuv,VladDrake/libyuv,dilagurung/libyuv,dilagurung/libyuv,uraran/libyuv,WangYongHai/libyuv,yzhikan/libyuv,hyper123/libyuv,mosterta/libyuv,VladDrake/libyuv,uditkumawat/libyuv,KerwinMa/libyuv,dilagurung/libyuv,fate-extra/libyuv,aberejohn/libyuv,KerwinMa/libyuv,Vairn/libyuv,alfahim/libyuv,KerwinMa/libyuv,bingerZhang/libyuv,OrenHg/libyuv,aberejohn/libyuv,mosterta/libyuv,Vairn/libyuv,yzhikan/libyuv,wl-chuang/libyuv,OrenHg/libyuv,gigakuma/libyuv,RockySteveJobs/libyuv,mosterta/libyuv,chucvv/libyuv,skufog/libyuv,hyper123/libyuv,sathishkumars3/libyuv,RockySteveJobs/libyuv,wl-chuang/libyuv,OrenHg/libyuv,fate-extra/libyuv,bingerZhang/libyuv,dexcz/libyuv,alfahim/libyuv,sathishkumars3/libyuv,syoshimu/libyuv,syoshimu/libyuv,ganzhijie/libyuv,sathishkumars3/libyuv,WangYongHai/libyuv,wl-chuang/libyuv,fate-extra/libyuv,hajunho/libyuv,StopProducing/libyuv,aberejohn/libyuv,skufog/libyuv,WangYongHai/libyuv,hajunho/libyuv,gigakuma/libyuv,uditkumawat/libyuv,uraran/libyuv,hajunho/libyuv