ACPICA: Remove duplicate extern declarations for public globals

Some were defined twice, causes a warning with gcc
-Wredundant-decls.

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/include/acpi/acpixf.h b/include/acpi/acpixf.h
index 82ec6a3..2aecaa5 100644
--- a/include/acpi/acpixf.h
+++ b/include/acpi/acpixf.h
@@ -64,6 +64,7 @@
 extern u8 acpi_gbl_all_methods_serialized;
 extern u8 acpi_gbl_create_osi_method;
 extern u8 acpi_gbl_leave_wake_gpes_disabled;
+extern u8 acpi_gbl_use_default_register_widths;
 extern acpi_name acpi_gbl_trace_method_name;
 extern u32 acpi_gbl_trace_flags;