[S390] cio: Re-start path verification after aborting internal I/O.

Path verification triggered by changes to the available CHPIDs will be
interrupted by another change but not re-started. This results in an
invalid path mask.
To solve this make sure to completely re-start path verification when
changing the available paths.

Signed-off-by: Stefan Bader <shbader@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>