OvmfPkg/Sec: Stop building identity mapped pages in SEC

OvmfPkg/Sec: Stop building identity mapped pages in SEC

Now for X64 we use a VTF0 ResetVector which puts the page
tables in RAM. Therefore SEC no longer needs to do this.

This reverts commit r14494.

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@14719 6f19259b-4bc3-4df7-8a09-765794883524