bnx2fc: use fcoe_link_speed_update() from the exported symbol in libfcoe

We have fcoe_link_speed_update() in libfcoe ready for use now, take out the
bnx2fc version which is almost the same.

Signed-off-by: Yi Zou <yi.zou@intel.com>
Cc: Bhanu Prakash Gollapudi <bprakash@broadcom.com>
Tested-by: Marcus Dennis <marcusx.e.dennis@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>