arch-arm: MPIDR.MT = 1 in a multithreaded system

MPIDR.MT Indicates whether the lowest level of affinity consists of
logical PEs that are implemented using a multithreading type approach

Change-Id: Ia5e6e65577729c7826227c4574ce690f76454edc
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/10502
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

src/arch/arm/utility.cc

@@ -223,6 +223,7 @@ getMPIDR(ArmSystem *arm_sys, ThreadContext *tc)
     assert(tc->socketId() < 65536);
     if (arm_sys->multiThread) {
        return 0x80000000 | // multiprocessor extensions available
+              0x01000000 | // multi-threaded cores
               tc->contextId();
     } else if (arm_sys->multiProc) {
        return 0x80000000 | // multiprocessor extensions available