bindings: thermal: Add compatible field for PMIC4 ADC_TM

Add new compatible field for PMIC4 ADC_TM as it needs to
be distinguished from PMIC5.

Change-Id: I8127c60cd32088d9f31652269e2d3a67adae569e
Signed-off-by: Jishnu Prakash <jprakash@codeaurora.org>
Signed-off-by: Asha Magadi Venkateshamurthy <amagad@codeaurora.org>