Maintainers.txt: Add missing Github IDs for OvmfPkg TPM/TGC modules

Maintainers.txt: Add missing Github IDs for OvmfPkg TPM/TGC modules

Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Cc: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Acked-by: Ard Biesheuvel <ardb+tianocore@kernel.org>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>