hte: Uninitialized variable in hte_ts_get()

The "free_name" variable is sometimes used without being initialized.

Fixes: 31ab09b4 ("drivers: Add hardware timestamp engine (HTE) subsystem")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Dipen Patel <dipenp@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>