Maintainers.txt: restore order of OvmfPkg sections

Maintainers.txt: restore order of OvmfPkg sections

The OvmfPkg subsystem / section headers are currently ordered in
Maintainers.txt as follows:

> OvmfPkg
> OvmfPkg: Xen-related modules
> OvmfPkg: TCG- and TPM2-related modules
> OvmfPkg: CSM modules
> OvmfPkg: MptScsi and PVSCSI driver

Restore the following (alphabetical) order between them:

> OvmfPkg
> OvmfPkg: CSM modules
> OvmfPkg: MptScsi and PVSCSI driver
> OvmfPkg: TCG- and TPM2-related modules
> OvmfPkg: Xen-related modules

Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Julien Grall <julien@xen.org>
Cc: Liran Alon <liran.alon@oracle.com>
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Cc: Nikita Leshenko <nikita.leshchenko@oracle.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Cc: Stefan Berger <stefanb@linux.ibm.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2778
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200603160627.3594-3-lersek@redhat.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Leif Lindholm <leif@nuviainc.com>