platform/loongarch: laptop: Explicitly reset bl_powered state when suspend

commit 91a70492c0 upstream.

On EAECIS NL60R with EC firmware version 1.11, resuming from S3 has a
very high chance (>90%) of causing the EC to lose the previous backlight
power state. When this happens, the laptop resumes normally from S3, but
the backlight remains off (when shining on the screen with a flash light,
we can see the screen contents are updating normally).

Since there is no generic way to query the EC's backlight state on
Loongson laptop platforms, assume the worst-case scenario and restart
the backlight power inside the kernel each time the system resumes.

Cc: stable@vger.kernel.org
Fixes: 53c762b47f ("platform/loongarch: laptop: Add backlight power control support")
Tested-by: Yao Zi <me@ziyao.cc>
Tested-by: Xi Ruoyao <xry111@xry111.site>
Signed-off-by: Zixing Liu <liushuyu@aosc.io>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/platform/loongarch/loongson-laptop.c

@@ -189,6 +189,7 @@ static int __init setup_acpi_notify(struct generic_sub_driver *sub_driver)
 
 static int loongson_hotkey_suspend(struct device *dev)
 {
+	bl_powered = false;
 	return 0;
 }