CoreStorage LVs, not CoreStorage PVs, should be set whole_disk=0.

When considering whether a device is a 'whole disk' in the ZFS sense,
we need to check for a CoreStorage Logical Volume (LV) not for a
CoreStorage Physical Volume (PV).

Checking for a CoreStorage PV is more appropriate if trying to detect
a pre-existing file system on a device, as we might do if adding
additional protections against accidentally supplying 'zpool create'
with the wrong device.