ACPI: AC: Remove the leftover struct acpi_ac_bl

In commit 57a1832222 ("ACPI / x86: Introduce an
acpi_quirk_skip_acpi_ac_and_battery() helper"), the usage of struct
acpi_ac_bl was removed, but left the definition of the struct in
the file, so remove the useless code.

Signed-off-by: Hanjun Guo <guohanjun@huawei.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/ac.c

@@ -36,11 +36,6 @@ static int acpi_ac_add(struct acpi_device *device);
 static int acpi_ac_remove(struct acpi_device *device);
 static void acpi_ac_notify(struct acpi_device *device, u32 event);
 
-struct acpi_ac_bl {
-	const char *hid;
-	int hrv;
-};
-
 static const struct acpi_device_id ac_device_ids[] = {
 	{"ACPI0003", 0},
 	{"", 0},