thermal/drivers/mediatek/lvts: Remove unused lvts_debugfs_exit

When debugfs is disabled, the function has no reference any more:

drivers/thermal/mediatek/lvts_thermal.c:266:13: error: 'lvts_debugfs_exit' defined but not used [-Werror=unused-function]
266 | static void lvts_debugfs_exit(struct lvts_domain *lvts_td) { }
| ^~~~~~~~~~~~~~~~~

Fixes: ef280c17a840 ("thermal/drivers/mediatek/lvts: Fix debugfs unregister on failure")
Signed-off-by: Arnd Bergmann <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Daniel Lezcano <[e-mail]>

drivers/thermal/mediatek/lvts_thermal.c

···
 	return 0;
 }
 
-static void lvts_debugfs_exit(struct lvts_domain *lvts_td) { }
-
 #endif
 
 static int lvts_raw_to_temp(u32 raw_temp, int temp_factor)