thermal: qpnp-adc-tm: Remove VADC_TM EOC

VADC_TM is used currently only for monitoring high/low
thresholds. Therefore remove registering for end of conversion
interrupts as we do not use this mode on VADC_TM.

Change-Id: Idf4afd23fa12439667f868666515c01eb7acbfad
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>