ixgbe: add missing braces

This patch adds missing braces around the 10gig link check to include the check for  KR support.

Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Reported-by: Sascha Wildner <saw@online.de>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>