cosmetics: Make libavcodec/ppc/dsputil_altivec.c conform to style guidelines.

This includes indentation changes, comment reformatting, consistent brace                                                                                                             
placement and some prettyprinting.


git-svn-id: file:///var/local/repositories/ffmpeg/trunk@14318 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b