ixgbe: Correct BASE-BX10 compliance code

SFF-8472 (section 5.4 Transceiver Compliance Codes) defines bit 6 as
BASE-BX10. Bit 6 means a value of 0x40 (decimal 64).

The current value in the source code is 0x64, which appears to be a
mix-up of hex and decimal values. A value of 0x64 (binary 01100100)
incorrectly sets bit 2 (1000BASE-CX) and bit 5 (100BASE-FX) as well.

Fixes: 1b43e0d2 ("ixgbe: Add 1000BASE-BX support")
Signed-off-by: Tore Amundsen <tore@amundsen.org>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Acked-by: Ernesto Castellotti <ernesto@castellotti.net>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>