examples/tls_client: add time log for performance measurement
examples/tls_client: add time log for performance measurement

Change-Id: I17698309c45bc9d20180046aa8883f21bfc01f58
Signed-off-by: Joohwan Kim <d8eb2057d34b4ed71c8b9c3943d864bbf0a7d8e6@samsung.com>

JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT,JunhwanPark/TizenRT