max8925_power: No temperature interrupts if temperature not connected

Brownstone does not have temperature reading circuit hooked up.
This leads to spurious interrupts.

Allow the platform layer to indicate no temperature circuit
and do not activate interrupts if no temperature control is set

Signed-off-by: Philip Rakity <prakity@marvell.com>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>