Description: Configuration  of  the  buffer size configuration for the high and
low  priority  cell.  The  sum  of  high  and  low priority buffers
capacity is fixed, i.e., highzero selection means low priority buffer
size being the maximum which is 32768 cells capacity. 4 possible 
way of partitioning the buffer:
   ________________________________
  |  High Priority | Low Priority |
  |_______________________________|
  |      0 cells   | 32768 cells  |
  |_______________________________|
  |   8192 cells   | 24576 cells  |
  |_______________________________|
  |  16384 cells   | 16384 cells  |
  |_______________________________|
  |  24576 cells   |  8192 cells  |
  |_______________________________|