If disable LSC when launching testpmd with X722, shown
link speed is 20G but not 10G. It's caused by wrongly
parsed link speed.
Correct it according to X722 datasheet.
Fixes: eef2daf2e199 ("net/i40e: fix link update no wait")
Cc: stable@dpdk.org
Signed-off-by: Beilei Xing <beilei.xing@intel.com>
Acked-by: Qi Zhang <qi.z.zhang@intel.com>