MFC r247159
  Improvements for newer mxge nics:

  - Some mxge nics may store the serial number in the SN2 field of the
    EEPROM.  These will also have an SN=0 field, so parse the SN2 field,
    and give it precedence.

  - Skip MXGEFW_CMD_UNALIGNED_TEST on mxge nics which do not require it.
    This saves roughly 10ms per port at device attach time.
MFC r247160

  Bump mxge copyright.