thermal: ti-soc-thermal: Set the bandgap mask counter delay value

Set the bandgap mask counter_delay with the polling_delay value on
registering the thermal zone. This patch will ensure to get the
correct update interval for computing the thermal trend.

Signed-off-by: Ranganath Krishnan <ranganath@ti.com>
Signed-off-by: Eduardo Valentin <eduardo.valentin@ti.com>