OvmfPkg: For OvmfPkgX64, use OvmfPkg/ResetVector

OvmfPkg: For OvmfPkgX64, use OvmfPkg/ResetVector

This reset vector code will build page tables in RAM at address
0x80000, rather than relying on page tables to be present within
the flash image.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@14717 6f19259b-4bc3-4df7-8a09-765794883524