ACPICA: Use %d for signed int print formatting instead of %u

Fix warnings found using static analysis with cppcheck, use %d printf
format specifier for signed ints rather than %u

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Erik Schmauss <erik.schmauss@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>