thermal: adc-tm: Correct a macro expression for PMIC7 ADC_TM

Correct expression in macro ADC_TM_UPPER_MASK. Correct
calculation of value written to ADC_TM measurement enable
register.

Change-Id: I14a6f585bb0cee678aa6eee749ba3e983ba47173
Signed-off-by: Jishnu Prakash <jprakash@codeaurora.org>