* Each HW Rx descriptor has many Rx buffers. The number of buffers
* in one HW Rx descriptor is equal to size of contiguous block
* provided by Rx buffers memory pool. The contiguous block size
* Each HW Rx descriptor has many Rx buffers. The number of buffers
* in one HW Rx descriptor is equal to size of contiguous block
* provided by Rx buffers memory pool. The contiguous block size