[boom] hacks to make boom work as a rocket Core.

   - A BOOM core has its own TLB. Which needs a TL2 edge. And a PTW port.
   - Add edge implicit input to Core.
   - Widen CoreIO to accept a ptw_tlb port.
   - Modify RocketCoreParams to handle wider fetchWidths, retireWidths.
   - Hack PTW requestor count to accommodate extra PTW port.
   - Wire up PTW requestor to the core's TLB in the Tile.