spapr-tpm-proxy: Drop misleading check

Coverity is reporting in CID 1405304 that tpm_execute() may pass a NULL
tpm_proxy->host_path pointer to open(). This is based on the fact that
h_tpm_comm() does a NULL check on tpm_proxy->host_path and then passes
tpm_proxy to tpm_execute().

The check in h_tpm_comm() is abusive actually since a spapr-proxy-tpm
requires a non NULL host_path property, as checked during realize.

Fixes: 0fb6bd073230
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <156805260916.1779401.11054185183758185247.stgit@bahia.lan>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

hw/ppc/spapr_tpm_proxy.c

@@ -114,7 +114,7 @@ static target_ulong h_tpm_comm(PowerPCCPU *cpu,
         return H_FUNCTION;
     }
 
-    trace_spapr_h_tpm_comm(tpm_proxy->host_path ?: "null", op);
+    trace_spapr_h_tpm_comm(tpm_proxy->host_path, op);
 
     switch (op) {
     case TPM_COMM_OP_EXECUTE: