Fix typo in r25019.

Patch by Eli Friedman <eli.friedman at gmail dot com>.

Originally committed as revision 25022 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/x86/h264_weight.asm

@@ -95,7 +95,7 @@ WEIGHT_FUNC_DBL_MM 16
 WEIGHT_FUNC_DBL_MM  8
 
 %macro WEIGHT_FUNC_MM 4
-cglobal h264_weight_%1x%2_%4, 7, 7, %
+cglobal h264_weight_%1x%2_%4, 7, 7, %3
     WEIGHT_SETUP
     mov        r2, %2
 %if %2 == 16