libdm: rename dm_stats name, devno and uuid members

libdm: rename dm_stats name, devno and uuid members

The device-mapper name, device numbers and uuid stored in the
dm_stats handle are used only to bind the handle to a specific
device in order to issue ioctls.

Rename them to "bind_*" to reflect this usage in preparation
for caching the device-mapper name of the bound device in the
dm_stats handle.

This will be used to allow optional aliases to be set for
dmstats groups.