nvme device support for statelite image

[vigo332]

The code share/xcat/netboot/add-on/statelite/rc.statelite assumes the device to be like sdx and partition number sdxN.
But for nvme devices like nvme0n1, the partition is nvme0n1p1, which has a 'p' padding.

The image fails with nvme devices for localdisk partition during boot, as it assumes nvme0n11, and failed to find.

A pull request is submitted for this. This pull request has been aided by @jjohnson42

[Obihoernchen]

#7477 merged