s390/pci: add extra padding to function measurement block

Newer machines might use a different (larger) format for function
measurement blocks. To ensure that we comply with the alignment
requirement on these machines and prevent memory corruption (when
firmware writes more data than we expect) add 16 padding bytes
at the end of the fmb.

Cc: stable@vger.kernel.org # v4.1+
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>