simplify Load8x4() a bit
simplify Load8x4() a bit

Change-Id: I68cf09c432f48e34bbe1d47dd091417cfd40cf4e

ttyangf/libwebp,imazen/libwebp,ttyangf/libwebp,yohunl/libwebp,ya7lelkom/libwebp,yohunl/libwebp,rxl194/libwebp,ya7lelkom/libwebp,ya7lelkom/libwebp,imazen/libwebp,redengineer/libwebp,rxl194/libwebp,webmproject/libwebp,rxl194/libwebp,imazen/libwebp,Aexyn/libwebp,rxl194/libwebp,imazen/libwebp,zofuthan/libwebp,PKRoma/libwebp,yohunl/libwebp,Aexyn/libwebp,rxl194/libwebp,Aexyn/libwebp,PKRoma/libwebp,redengineer/libwebp,ttyangf/libwebp,zofuthan/libwebp,webmproject/libwebp,ya7lelkom/libwebp,PKRoma/libwebp,Aexyn/libwebp,PKRoma/libwebp,webmproject/libwebp,yohunl/libwebp,webmproject/libwebp,webmproject/libwebp,redengineer/libwebp,redengineer/libwebp,zofuthan/libwebp,ttyangf/libwebp,zofuthan/libwebp,Aexyn/libwebp,PKRoma/libwebp,ttyangf/libwebp,ya7lelkom/libwebp,yohunl/libwebp,zofuthan/libwebp,imazen/libwebp,redengineer/libwebp,PKRoma/libwebp