memory: Add global-locking property to memory regions

memory: Add global-locking property to memory regions

This introduces the memory region property "global_locking". It is true
by default. By setting it to false, a device model can request BQL-free
dispatching of region accesses to its r/w handlers. The actual BQL
break-up will be provided in a separate patch.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Frederic Konrad <fred.konrad@greensocs.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1434646046-27150-4-git-send-email-pbonzini@redhat.com>