ACPICA: Fail AcpiEnable if ACPI tables not loaded.

AcpiEnable will now fail if all of the required ACPI tables are not
loaded (FADT, FACS, DSDT). BZ 477

Signed-off-by: Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/include/acpi/actables.h b/include/acpi/actables.h
index 5ef1b69..e7efb8a0 100644
--- a/include/acpi/actables.h
+++ b/include/acpi/actables.h
@@ -97,6 +97,8 @@
 /*
  * tbutils - table manager utilities
  */
+u8 acpi_tb_tables_loaded(void);
+
 void
 acpi_tb_print_table_header(acpi_physical_address address,
 			   struct acpi_table_header *header);