ACPICA: acpi_madt_oem_data: Fix flexible array member definition

ACPICA commit e7f6d8c1b7f79eb4b9b07f1bc09c549a2acbd6e8

Use ACPI_FLEX_ARRAY() helper to define flexible array member alone in a
struct. Fixes issue #812.

No binary changes appear in the .text nor .data sections.

Link: acpica/acpica@e7f6d8c1
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: kees

include/acpi/actbl2.h

@@ -1274,7 +1274,7 @@ enum acpi_madt_rintc_version {
 /* 80: OEM data */
 
 struct acpi_madt_oem_data {
-	u8 oem_data[0];
+	ACPI_FLEX_ARRAY(u8, oem_data);
 };
 
 /*