bindings: Documentation: Add documentation for qpnp-adc-tm nodes

Add snapshot of qpnp-adc-tm driver from msm-4.9
'commit 7e65e03259909 (Merge "msm: kgsl: Deregister gpu
address on memdesc_sg_virt failure")'.

Adc-tm driver provides interface to thermal clients to
set temperature thresholds.

Change-Id: Ifb4d8f4e21fdbf9bdf02e30aafb7b39617c6ca5f