net/igc: fix speed configuration
net/igc: fix speed configuration

Fixed speed mode is not supported currently, this patch
removes configurations for this mode and adds fault handling
for ETH_LINK_SPEED_FIXED.

Fixes: 4f09bc55ac3d ("net/igc: implement device base operations")
Cc: stable@dpdk.org

Signed-off-by: Alvin Zhang <c5463347bfd64f7a052e86eaaf49a5760efc9625@intel.com>
Acked-by: Junfeng Guo <4e83c95a099a2e36f95a0baa7b159dfaca2b98e9@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk