thermal/core: Introduce non-OF thermal_cooling_device_register()

thermal/core: Introduce non-OF thermal_cooling_device_register()

Split the cooling device registration API into OF and non-OF variants.

Introduce thermal_cooling_device_register() for non-device-tree users
and rework thermal_of_cooling_device_register() to use the new
alloc/add split.

This removes the need for the internal __thermal_cooling_device_register()
helper and makes the separation between OF and non-OF users explicit.

Signed-off-by: Daniel Lezcano <daniel.lezcano@oss.qualcomm.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@kernel.org>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Acked-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Link: https://patch.msgid.link/20260526140802.1059293-13-daniel.lezcano@oss.qualcomm.com