libfcoe, fcoe: move fcoe_link_speed_update() to libfcoe and export it

With the previous patch, fcoe_link_speed_update() can be moved into libfcoe and
exported to used by fcoe, bnx2fc, and etc.

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>
diff --git a/include/scsi/libfcoe.h b/include/scsi/libfcoe.h
index 746bc58..6c59ba7 100644
--- a/include/scsi/libfcoe.h
+++ b/include/scsi/libfcoe.h
@@ -260,6 +260,7 @@
 		     struct net_device *netdev);
 void fcoe_wwn_to_str(u64 wwn, char *buf, int len);
 int fcoe_validate_vport_create(struct fc_vport *vport);
+int fcoe_link_speed_update(struct fc_lport *);
 
 /**
  * is_fip_mode() - returns true if FIP mode selected.