eal: rename thread TLS API

eal: rename thread TLS API

Rename the key opaque pointer from rte_tls_key to
rte_thread_key to avoid confusion with transport layer security.

Also rename and remove the "_tls" term from the following
functions to avoid redundancy:

rte_thread_tls_key_create
rte_thread_tls_key_delete
rte_thread_tls_value_set
rte_thread_tls_value_get

Suggested-by: Vladimir Medvedkin <vladimir.medvedkin@intel.com>
Suggested-by: Morten Brørup <mb@smartsharesystems.com>
Signed-off-by: Tal Shnaiderman <talshn@nvidia.com>
Acked-by: Morten Brørup <mb@smartsharesystems.com>