o Use mbufs, for the RX ring, instead of malloc()'ing an MCLBYTES sized buffer.

o Use mbufs, for the RX ring, instead of malloc()'ing an MCLBYTES sized buffer.
o On non-strict alignment archs, dont copy the mbuf, every time, unload it, and send
  it up the stack and just get a new one for the rx ring. We still do the copy on
  strict alignment archs though...
o create a function to handle mbuf allocation for the rx ring, vr_mbuf_alloc(),
  use it to allocate the mbufs and shuffle the bus dma setup around.

ideas/code from vic(4) and sis(4);

ok reyk@, brad@, dlg@
tested by many, been in snapshots for a while.