OvmfPkg/VirtioNetDxe: Fix build errors on VS2012 (IA32 & X64)

These changes were needed in addition to the silence.patch
that Laszlo posted on May 28.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@14420 6f19259b-4bc3-4df7-8a09-765794883524
3 files changed