lavu/hwcontext_d3d: Cast src pointers calling av_image_copy*().

Silences several warnings:
libavutil/hwcontext_d3d11va.c:413:49: warning: passing argument 3 of ‘av_image_copy’ from incompatible pointer type
libavutil/hwcontext_d3d11va.c:425:47: warning: passing argument 3 of ‘av_image_copy’ from incompatible pointer type
libavutil/hwcontext_dxva2.c:351:45: warning: passing argument 3 of ‘av_image_copy’ from incompatible pointer type
libavutil/hwcontext_dxva2.c:382:52: warning: passing argument 3 of ‘av_image_copy_uc_from’ from incompatible pointer type

libavutil/hwcontext_d3d11va.c

@@ -410,7 +410,7 @@ static int d3d11va_transfer_data(AVHWFramesContext *ctx, AVFrame *dst,
 
         fill_texture_ptrs(map_data, map_linesize, ctx, &desc, &map);
 
-        av_image_copy(dst->data, dst->linesize, map_data, map_linesize,
+        av_image_copy(dst->data, dst->linesize, (const uint8_t **)map_data, map_linesize,
                       ctx->sw_format, w, h);
 
         ID3D11DeviceContext_Unmap(device_hwctx->device_context, staging, 0);
@@ -422,7 +422,7 @@ static int d3d11va_transfer_data(AVHWFramesContext *ctx, AVFrame *dst,
 
         fill_texture_ptrs(map_data, map_linesize, ctx, &desc, &map);
 
-        av_image_copy(map_data, map_linesize, src->data, src->linesize,
+        av_image_copy(map_data, map_linesize, (const uint8_t **)src->data, src->linesize,
                       ctx->sw_format, w, h);
 
         ID3D11DeviceContext_Unmap(device_hwctx->device_context, staging, 0);

libavutil/hwcontext_dxva2.c

@@ -348,7 +348,7 @@ static int dxva2_transfer_data_to(AVHWFramesContext *ctx, AVFrame *dst,
     if (ret < 0)
         goto fail;
 
-    av_image_copy(map->data, map->linesize, src->data, src->linesize,
+    av_image_copy(map->data, map->linesize, (const uint8_t **)src->data, src->linesize,
                   ctx->sw_format, src->width, src->height);
 
 fail:
@@ -379,7 +379,7 @@ static int dxva2_transfer_data_from(AVHWFramesContext *ctx, AVFrame *dst,
         dst_linesize[i] = dst->linesize[i];
         src_linesize[i] = map->linesize[i];
     }
-    av_image_copy_uc_from(dst->data, dst_linesize, map->data, src_linesize,
+    av_image_copy_uc_from(dst->data, dst_linesize, (const uint8_t **)map->data, src_linesize,
                           ctx->sw_format, src->width, src->height);
 fail:
     av_frame_free(&map);