x86: Add a header guard to asm/acpi_table.h

This file cannot currently be included in ASL files. Add a header guard
to permit this.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

arch/x86/include/asm/acpi_table.h

@@ -9,6 +9,8 @@
 #ifndef __ASM_ACPI_TABLE_H__
 #define __ASM_ACPI_TABLE_H__
 
+#ifndef __ACPI__
+
 struct acpi_facs;
 struct acpi_fadt;
 struct acpi_global_nvs;
@@ -213,4 +215,6 @@ void acpi_fadt_common(struct acpi_fadt *fadt, struct acpi_facs *facs,
  */
 void intel_acpi_fill_fadt(struct acpi_fadt *fadt);
 
+#endif /* !__ACPI__ */
+
 #endif /* __ASM_ACPI_TABLE_H__ */