ixgbe: add support for 1G SX modules

This patch adds support for 1G Fiber PHY modules (SFP+ modules). This support
comes along side support for 1G Copper PHY modules, but uses a different PHY
type (ixgbe_sfp_type_1g_sx_core).

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>