e1000e: suppress compile warnings on certain archs

Commit 84f4ee90 causes compile warnings on
architectures that have unsigned long long's that are not 64-bit, e.g.
ia64.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>