thermal: rcar_gen3_thermal: disable interrupt in .remove

Currently IRQ remains enabled after .remove, later if device is probed,
IRQ is requested before .thermal_init, this may cause IRQ function be
called before device is initialized.

this patch disables interrupt in .remove, to ensure irq function
only be called after device is fully initialized.

Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>