Improve the comments of Thermal HAL 2.0 API

Make sure (un)register API failed with nullptr

Test: Build
Test: VtsHalThermalV2_0TargetTest
Change-Id: I42a87fde85a38f77faa4d07f29ed3a78501a0dca
diff --git a/current.txt b/current.txt
index a128669..be71351 100644
--- a/current.txt
+++ b/current.txt
@@ -534,7 +534,7 @@
 ae5faa38538a9f50eb71eb7f9b998271124d2c64b761cb11c4d820c7732b4ddc android.hardware.sensors@2.0::ISensorsCallback
 3a98242a57d0820dacaca0f7db52bec433eae1f21c498763c6f1ece611c3967b android.hardware.sensors@2.0::types
 ce4b98211959449361146d4b1e5554dc841ceb4d4577154d7b2fb6d1eb504f76 android.hardware.soundtrigger@2.2::ISoundTriggerHw
-5cc81d517c5f3fef12e719b0f5683c7c99e3e8895fcb80e6f6653b454f463320 android.hardware.thermal@2.0::IThermal
+bd88b48639cae30982021024e22371076c76faa8466e38ca598529452b618eae android.hardware.thermal@2.0::IThermal
 cc4d2ef36da776c475ad054f0f3416d8a8865def9d9e2129f10074b28e36d203 android.hardware.thermal@2.0::IThermalChangedCallback
 b47f90302595874dfddb19bd05a054727bf18b3a930bc810ea14957b859ae8bf android.hardware.thermal@2.0::types
 61bc302e7c974c59b25898c585c6e9685e8a81021b1bed3eedf5224198f2785a android.hardware.usb@1.2::IUsb