e1000: Silence sparse warnings by correcting type

Silence sparse warnings shown below:
...
drivers/net/ethernet/intel/e1000/e1000_main.c:3435:17: warning:
	cast to restricted __le64
drivers/net/ethernet/intel/e1000/e1000_main.c:3435:17: warning:
	cast to restricted __le64
...

Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>