lavc/aarch64/h264dsp_init_aarch64: Fix weight function prototypes.

lavc/aarch64/h264dsp_init_aarch64: Fix weight function prototypes.

Fixes the following warnings:
libavcodec/aarch64/h264dsp_init_aarch64.c: In function ‘ff_h264dsp_init_aarch64’:
libavcodec/aarch64/h264dsp_init_aarch64.c:84:38: warning: assignment from incompatible pointer type [enabled by default]
         c->weight_h264_pixels_tab[0] = ff_weight_h264_pixels_16_neon;
                                      ^
libavcodec/aarch64/h264dsp_init_aarch64.c:85:38: warning: assignment from incompatible pointer type [enabled by default]
         c->weight_h264_pixels_tab[1] = ff_weight_h264_pixels_8_neon;
                                      ^
libavcodec/aarch64/h264dsp_init_aarch64.c:86:38: warning: assignment from incompatible pointer type [enabled by default]
         c->weight_h264_pixels_tab[2] = ff_weight_h264_pixels_4_neon;
                                      ^
libavcodec/aarch64/h264dsp_init_aarch64.c:88:40: warning: assignment from incompatible pointer type [enabled by default]
         c->biweight_h264_pixels_tab[0] = ff_biweight_h264_pixels_16_neon;
                                        ^
libavcodec/aarch64/h264dsp_init_aarch64.c:89:40: warning: assignment from incompatible pointer type [enabled by default]
         c->biweight_h264_pixels_tab[1] = ff_biweight_h264_pixels_8_neon;
                                        ^
libavcodec/aarch64/h264dsp_init_aarch64.c:90:40: warning: assignment from incompatible pointer type [enabled by default]
         c->biweight_h264_pixels_tab[2] = ff_biweight_h264_pixels_4_neon;
                                        ^