ixgbe: add 1Gbps support for QSFP+

This patch adds GB speed support for QSFP+ modules.
Autonegotiation is not supported with QSFP+. The user will have to set
the desired speed on both link partners using ethtool advertise setting.

Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>