thermal: testing: Initialize some variables annoteded with _free()

Variables annotated with __free() need to be initialized if the function
can return before they get updated for the first time or the attempt to
free the memory pointed to by them upon function return may crash the
kernel.

Fix this issue in some places in the thermal testing code.

Fixes: f6a034f2df42 ("thermal: Introduce a debugfs-based testing facility")
Reported-by: Dan Carpenter <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>
Link: https://patch.msgid.link/[e-mail]

drivers/thermal/testing/zone.c

···
 int tt_add_tz(void)
 {
 	struct tt_thermal_zone *tt_zone __free(kfree);
-	struct tt_work *tt_work __free(kfree);
+	struct tt_work *tt_work __free(kfree) = NULL;
 	int ret;
 
 	tt_zone = kzalloc(sizeof(*tt_zone), GFP_KERNEL);
···
 
 int tt_del_tz(const char *arg)
 {
-	struct tt_work *tt_work __free(kfree);
+	struct tt_work *tt_work __free(kfree) = NULL;
 	struct tt_thermal_zone *tt_zone, *aux;
 	int ret;
 	int id;
···
 int tt_zone_add_trip(const char *arg)
 {
 	struct tt_thermal_zone *tt_zone __free(put_tt_zone) = NULL;
+	struct tt_trip *tt_trip __free(kfree) = NULL;
 	struct tt_work *tt_work __free(kfree);
-	struct tt_trip *tt_trip __free(kfree);
 	int id;
 
 	tt_work = kzalloc(sizeof(*tt_work), GFP_KERNEL);
···
 
 static int tt_zone_register_tz(struct tt_thermal_zone *tt_zone)
 {
-	struct thermal_trip *trips __free(kfree);
+	struct thermal_trip *trips __free(kfree) = NULL;
 	struct thermal_zone_device *tz;
 	struct tt_trip *tt_trip;
 	int i;