i40evf: clean up memsets

As politely pointed out by Dave Miller, calls to memset do not need a
void pointer cast. Additionally, it is preferred to use sizeof(*the
actual object) instead of sizeof(type).

Change-ID: Id6a02429b7040111531f3865ea03fbe619167cb3
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Signed-off-by: Kevin Scott <kevin.c.scott@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Kavindya Deegala <kavindya.s.deegala@intel.com>
Signed-off-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>