OvmfPkg: PlatformPei: reuse PublishPeiMemory() in MemDetect()

OvmfPkg: PlatformPei: reuse PublishPeiMemory() in MemDetect()

Although SVN r14944 ("OvmfPkg: introduce PublishPeiMemory") copied a big
chunk of code from MemDetect(), calling the new PublishPeiMemory()
function in MemDetect() could not have replaced the original code in the
latter. However, with the help of the previous patch, we can do it now.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15023 6f19259b-4bc3-4df7-8a09-765794883524