avutil/hwcontext_d3d11va: correct sizeof AVD3D11FrameDescriptor

Fixes: CID1591909 Wrong sizeof argument

Sponsored-by: Sovereign Tech Fund
Reviewed-by: Steve Lhomme <robux4@ycbcr.xyz>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 698ed0d5a5)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavutil/hwcontext_d3d11va.c

@@ -201,7 +201,7 @@ static AVBufferRef *wrap_texture_buf(AVHWFramesContext *ctx, ID3D11Texture2D *te
     desc->texture = tex;
     desc->index   = index;
 
-    buf = av_buffer_create((uint8_t *)desc, sizeof(desc), free_texture, tex, 0);
+    buf = av_buffer_create((uint8_t *)desc, sizeof(*desc), free_texture, tex, 0);
     if (!buf) {
         ID3D11Texture2D_Release(tex);
         av_free(desc);