ixgb: enable sun hardware support for broadcom phy

Implement support for a SUN-specific PHY.

SUN provides a modified 82597-based board with their own
PHY that works with very little modification to the code. This
patch implements this new PHY which is identified by the
subvendor device ID. The device ID of the adapter remains
the same.

Signed-off-by: Matheos Worku <matheos.worku@sun.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>