s390/cio: update measurement characteristics

s390/cio: update measurement characteristics

BugLink: http://bugs.launchpad.net/bugs/1541534
Per channel path measurement characteristics are obtained during channel
path registration. However if some properties of a channel path change
we don't update the measurement characteristics.

Make sure to update the characteristics when we change the properties of
a channel path or receive a notification from FW about such a change.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
(cherry picked from commit 9f3d6d7a40a178b8a5b5274f4e55fec8c30147c9)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>