tpm: Make sure new locality passed to tpm_tis_prep_abort() is valid

Make sure that the new locality passed to tpm_tis_prep_abort()
is valid.

Add a comment to aborting_locty that it may be any locality, including
TPM_TIS_NO_LOCALITY.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
(cherry picked from commit e92b63e)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

hw/tpm/tpm_tis.c

@@ -263,7 +263,9 @@ static void tpm_tis_prep_abort(TPMState *s, uint8_t locty, uint8_t newlocty)
 {
     uint8_t busy_locty;
 
-    s->aborting_locty = locty;
+    assert(TPM_TIS_IS_VALID_LOCTY(newlocty));
+
+    s->aborting_locty = locty; /* may also be TPM_TIS_NO_LOCALITY */
     s->next_locty = newlocty;  /* locality after successful abort */
 
     /*