s390: nvme reipl

Populate sysfs and structs with reipl entries for nvme ipl type.
This allows specifying a target nvme device when rebooting/reipling.

Signed-off-by: Jason J. Herne <jjherne@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>