MFC r217296:

MFC r217296:
  For re(4) controllers that uses new jumbo frame scheme(RTL8168C/D/E),
  limit maximum RX buffer size to RE_RX_DESC_BUFLEN instead of
  blindly configuring it to 16KB. Due to lack of documentation, re(4)
  didn't allow jumbo frame on these controllers. However it seems
  controller is confused with jumbo frame such that it can DMA the
  received frame to wrong address instead of splitting it into
  multiple RX buffers. Of course, this caused panic.

  Since re(4) does not support jumbo frames on these controllers,
  make controller drop frame that is longer than RE_RX_DESC_BUFLEN
  sized frame. Fortunately RTL810x controllers, which do not support
  jumbo frame, have no such issues but this change also limited
  maximum RX buffer size allowed to RTL810x controllers. Allowing
  16KB RX buffer for controllers that have no such capability is
  meaningless.

Approved by:	re (bz)

git-svn-id: svn://svn.freebsd.org/base/releng/8.2@217647 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f