video_chroma: davinci_resizer: optimize

Optimize division by 2 with a right shift by 1.

modules/video_chroma/davinci.c

@@ -256,12 +256,12 @@ static int Init( filter_t *p_filter, picture_t *p_source, picture_t *p_dest )
      */
     rsz_params_t params;
     memset( &params, 0, sizeof( params ) );
-    params.in_hsize = p_source->p->i_visible_pitch / 2;
+    params.in_hsize = p_source->p->i_visible_pitch >> 1;
     params.in_vsize = p_source->p->i_visible_lines;
     params.in_pitch = p_source->p->i_pitch;
     params.inptyp = RSZ_INTYPE_YCBCR422_16BIT;
     params.pix_fmt = RSZ_PIX_FMT_YUYV;
-    params.out_hsize = p_dest->p->i_visible_pitch / 2;
+    params.out_hsize = p_dest->p->i_visible_pitch >> 1;
     params.out_vsize = p_dest->p->i_visible_lines;
     params.out_pitch = p_dest->p->i_pitch;