platform/loongarch: laptop: Unregister generic_sub_drivers on exit

commit f78fb25 upstream.

Without correct unregisteration, ACPI notify handlers and the platform
drivers installed by generic_subdriver_init() will become dangling
references after removing the loongson_laptop module, triggering various
kernel faults when a hotkey is sent or at kernel shutdown.

Cc: stable@vger.kernel.org
Fixes: 6246ed0 ("LoongArch: Add ACPI-based generic laptop driver")
Signed-off-by: Yao Zi <ziyao@disroot.org>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 782baee5d91765bf4ca9469b027cbc44080cbc95)

Author: ziyao233

drivers/platform/loongarch/loongson-laptop.c

@@ -611,11 +611,17 @@ static int __init generic_acpi_laptop_init(void)
 
 static void __exit generic_acpi_laptop_exit(void)
 {
+	int i;
+
 	if (generic_inputdev) {
-		if (input_device_registered)
-			input_unregister_device(generic_inputdev);
-		else
+		if (!input_device_registered) {
 			input_free_device(generic_inputdev);
+		} else {
+			input_unregister_device(generic_inputdev);
+
+			for (i = 0; i < ARRAY_SIZE(generic_sub_drivers); i++)
+				generic_subdriver_exit(&generic_sub_drivers[i]);
+		}
 	}
 }