e1000e: cosmetic change to boolean comparisons

Recent discussions on LKML, kernel-janitors, linux-wireless and netdev
have suggested boolean comparisons should use logical operators instead of
equality comparisons with true/false.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>