ixgbe: Add 10G-BX support

ixgbe: Add 10G-BX support

Add support for 10G-BX modules, i.e. 10GBit Ethernet over a single strand
Single-Mode fiber.
The initialization of a 10G-BX SFP+ is the same as for a 10G SX/LX module,
and is identified according to SFF-8472 table 5-3, footnote 3 by the
10G Ethernet Compliance Codes field being empty, the Nominal Bit
Rate being compatible with 12.5GBit, and the module being a fiber module
with a Single Mode fiber link length.

This was tested using a Lightron WSPXG-HS3LC-IEA 1270/1330nm 10km
transceiver:
$ sudo ethtool -m enp1s0f1
   Identifier                          : 0x03 (SFP)
   Extended identifier                 : 0x04 (GBIC/SFP defined by 2-wire interface ID)
   Connector                           : 0x07 (LC)
   Transceiver codes                   : 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
   Encoding                            : 0x01 (8B/10B)
   BR Nominal                          : 10300MBd
   Rate identifier                     : 0x00 (unspecified)
   Length (SMF)                        : 10km
   Length (OM2)                        : 0m
   Length (OM1)                        : 0m
   Length (Copper or Active cable)     : 0m
   Length (OM3)                        : 0m
   Laser wavelength                    : 1330nm
   Vendor name                         : Lightron Inc.
   Vendor OUI                          : 00:13:c5
   Vendor PN                           : WSPXG-HS3LC-IEA
   Vendor rev                          : 0000
   Option values                       : 0x00 0x1a
   Option                              : TX_DISABLE implemented
   BR margin max                       : 0%
   BR margin min                       : 0%
   Vendor SN                           : S142228617
   Date code                           : 140611
   Optical diagnostics support         : Yes

Signed-off-by: Birger Koblitz <mail@birger-koblitz.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Tested-by: Rinitha S <sx.rinitha@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>