[mpp_buf_slot]: set fbc size to mpp_frame

Signed-off-by: Yandong Lin <yandong.lin@rock-chips.com>
Change-Id: Iaf1b8ef0c1687af6a7532a706e3b9e688bf9745c

mpp/base/mpp_buf_slot.cpp

@@ -333,6 +333,7 @@ static void generate_info_set(MppBufSlotsImpl *impl, MppFrame frame, RK_U32 forc
             mpp_err("dec out fmt is no support");
         } break;
         }
+        mpp_frame_set_fbc_size(frame, size);
     } else {
         size *= impl->numerator;
         size /= impl->denominator;