ixgbe: Simplify port-specific macros

Simplify port-specific macros by eliminating explicit comparison
with 0. More importantly, enclose formal parameter in parens to
eliminate the risk of an operator precedence surprise.

Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>