tpm-ppi: page-align PPI RAM

tpm-ppi: page-align PPI RAM

post-copy migration fails on destination with error such as:
2019-12-26T10:22:44.714644Z qemu-kvm: ram_block_discard_range:
Unaligned start address: 0x559d2afae9a0

Use qemu_memalign() to constrain the PPI RAM memory alignment.

Cc: qemu-stable@nongnu.org
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Message-id: 20200103074000.1006389-3-marcandre.lureau@redhat.com
(cherry picked from commit 71e415c8a75c130875f14d6b2136825789feb297)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>