ixgbe: Fix reporting of 100Mb capability

BaseT adapters that are capable of supporting 100Mb are not reporting this
capability.  This patch corrects the reporting so that 100Mb is shown as
supported on those adapters.

Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>