thermal/core: Remove pointless variable when registering a cooling device

thermal/core: Remove pointless variable when registering a cooling device

The 'id' variable is set to store the ida_alloc() value which is
already stored into cdev->id. It is pointless to use it because
cdev->id can be used instead.

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>
Link: https://patch.msgid.link/20260402084426.1360086-1-daniel.lezcano@kernel.org
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>