ACPICA: remove duplicate u8 typedef

During commit e252652f ("ACPICA: acpidump: Remove integer types
translation protection.") two 'unsigned char' types got converted to 'u8'.

The result does not compile with gcc-4.5, it can not cope with duplicate
typedefs.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>