thermal: Fix QTI thermal crashing system on boot

* Probably due to some firmware issue, a thermal zone may not get
  populated with temperature. The value of temp is fcking space and
  HAL starts crashing while trying to read it (as length > 0)
* Proper fix would be trimming the buffer of any spaces or finding out
  why temp didn't populate in first place.

Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
Change-Id: If6e8d05ba24bd929deb9fde8f20deb939120d153