ixgbe/base: update EEE/FEC support for X550EM_X_KR

ixgbe/base: update EEE/FEC support for X550EM_X_KR

EEE(Energy Efficient Ethernet) is not supported on the initial revision
of IXGBE_DEV_ID_X550EM_X_KR. We determine the revision by reading a fuse
register.

Also, the requirements for FEC(Forward Error Correction) have changed
slightly. Now, we don't change the "request" bit at all. When EEE is
enabled, we advertise that we are capable. When EEE is disabled, we do
not advertise that we are capable. This change makes us consistent with
the power-on defaults that are in the NVM.

Signed-off-by: Wenzhuo Lu <wenzhuo.lu@intel.com>
Acked-by: Helin Zhang <helin.zhang@intel.com>