Fix#1384.
MESI_Two_Level and MESI_Three_Level protocols are susceptible to LL/SC
livelocks when simulating boards with high core count.
This fix is based on MOESI_CMP_directory's implementation of locked
states, but tailors the solution to only apply it when a Load-Linked is
initiated.
There are two new states to act as locked states and stall any messages
leading to eviction:
* LLSC_E: equivalent to E state, go to E after timeout.
* LLSC_M: equivalent to M state, go to M after timeout.
The main new event is Load_Linked, which is very similar (in behavior)
to a Store, reusing several transient states. When a controller receives
the exclusive data, it differentiates a Load_Linked from a Store by
checking a new field added to the TBE: 'isLoadLinked'. It triggers a
different event when it is a Load_Linked, which in turn causes the
transition to one of the locked states.
The entire mechanism can be turned off by setting 'use_llsc_lock' to
false, and the amount of time to keep locked is defined by
'llsc_lock_timeout_latency'.
Change-Id: I13f415b6b7890d51d01f23001047d2363467a814
7bddc764cc