e1000e: checkpatch warnings - braces

WARNING: braces {} are not necessary for any arm of this statement
WARNING: braces {} are not necessary for single statement blocks

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Emil Tantilov <emil.s.tantilov@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>