s390x/tcg: Save vregs to extended mchk save area

s390x/tcg: Save vregs to extended mchk save area

If we have vector registers and the designation is not zero, we have
to try to write the vector registers. If the designation is zero or
if storing fails, we must not indicate validity. s390_build_validity_mcic()
automatically already sets validity if the vector instruction facility
is installed.

As long as we don't support the guarded-storage facility, the alignment
and size of the area is always 1024 bytes.

Signed-off-by: David Hildenbrand <[email protected]>
Message-Id: <20190222081153[email protected]>
Reviewed-by: Thomas Huth <[email protected]>
Signed-off-by: Cornelia Huck <[email protected]>