purge-cluster: fix grep match for NVMe and HP Smart Array devices

purge-cluster: fix grep match for NVMe and HP Smart Array devices

raw_device would return invalid block device names for NVMe and HPSA
devices which would cause sgdisk partition deletion to fail

$ echo /dev/nvme1n1p3 | egrep -o '/dev/([hsv]d[a-z]{1,2}|cciss/c[0-9]d[0-9]p|nvme[0-9]n[0-9]p){1,2}'
/dev/nvme1n1p

$ echo /dev/cciss/c0d0p2 |  egrep -o '/dev/([hsv]d[a-z]{1,2}|cciss/c[0-9]d[0-9]p|nvme[0-9]n[0-9]p){1,2}'
/dev/cciss/c0d0p