platform/x86: panasonic-laptop: Use acpi_video_get_backlight_type()

Use acpi_video_get_backlight_type() to determine if we should register
the panasonic specific backlight interface. To avoid registering this
on systems where the ACPI or GPU native backlight control methods
should be used instead.
Tested-by: Stefan Seyfried <seife+kernel@b1-systems.com>
Tested-by: Kenneth Chan <kenneth.t.chan@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220624112340.10130-8-hdegoede@redhat.com

drivers/platform/x86/panasonic-laptop.c

@@ -998,10 +998,13 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
 		pr_err("Couldn't retrieve BIOS data\n");
 		goto out_input;
 	}
+
+	if (acpi_video_get_backlight_type() == acpi_backlight_vendor) {
 		/* initialize backlight */
 		memset(&props, 0, sizeof(struct backlight_properties));
 		props.type = BACKLIGHT_PLATFORM;
 		props.max_brightness = pcc->sinf[SINF_AC_MAX_BRIGHT];
+
 		pcc->backlight = backlight_device_register("panasonic", NULL, pcc,
 							   &pcc_backlight_ops, &props);
 		if (IS_ERR(pcc->backlight)) {
@@ -1011,6 +1014,7 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
 
 		/* read the initial brightness setting from the hardware */
 		pcc->backlight->props.brightness = pcc->sinf[SINF_AC_CUR_BRIGHT];
+	}
 
 	/* Reset initial sticky key mode since the hardware register state is not consistent */
 	acpi_pcc_write_sset(pcc, SINF_STICKY_KEY, 0);