h264: Fix pointer warnings by removing redundant [0]

Fixes:
h264.h:1222:38: warning: initialization from incompatible pointer type
h264.h:1299:38: warning: initialization from incompatible pointer type
h264.h:1314:42: warning: initialization from incompatible pointer type

Originally committed as revision 21814 to svn://svn.ffmpeg.org/ffmpeg/trunk