s390/dasd: Store path configuration data during path handling

Currently, the configuration data for a path is retrieved during a path
verification and used only temporarily. If a path is newly added to the
I/O setup after a boot, no configuration data will be stored for this
particular path.
However, this data is required for later use and should be present for
a valid I/O path anyway. Store this data during the path verification so
that newly added paths can provide all information necessary.

[sth@linux.ibm.com: fix conf_data memleak]

Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>