thermal/drivers/rcar_gen3_thermal: Create device local ops struct

The callback operations are modified on a driver global level. If one
device tree description do not define interrupts, the set_trips()
operation was disabled globally for all users of the driver.

Fix this by creating a device local copy of the operations structure and
modify the copy depending on what the device can do.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20230208190333.3159879-3-niklas.soderlund+renesas@ragnatech.se
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>