ANDROID: GKI: drivers: thermal: Add support for getting trip temperature

Add support for the sensor drivers using of-thermal interface to support
reading the trip temperature from the hardware using a callback. This
can be used in case, when the hardware works on a pre-configured
threshold different from the threshold set by software.

Test: build
Bug: 149945768
Change-Id: Ic5aaf1586b8dcbb3da0dd775718407c257b2064f
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>
(cherry picked from commit 8a12149c264c7b871932ad90f76e5981452bb4bb)
[hridya: added an extra null pointer check, partial cherry-pick]
Signed-off-by: Hridya Valsaraju <hridya@google.com>