videorate: keep pool if max_buffers is unlimited
The value 0 for max_buffers means unlimited. If the max_buffers are unlimited, the videorate element shouldn't throw away the bufferpool, but just increase the min_buffers value.
The value 0 for max_buffers means unlimited. If the max_buffers are unlimited, the videorate element shouldn't throw away the bufferpool, but just increase the min_buffers value.