s390/vdso: Use one large alternative instead of an alternative branch

s390/vdso: Use one large alternative instead of an alternative branch

Replace the alternative branch with a larger alternative that contains
both paths. That way the two paths are closer together and it is easier
to change both paths if the need should arise.

Signed-off-by: Heiko Carstens <[email protected]>
Reviewed-by: Jens Remus <[email protected]>
Signed-off-by: Vasily Gorbik <[email protected]>