tpm: Zero-init structure to avoid uninitialized variables in valgrind log

Zero-init the ptm_loc structure so that we don't have fields that
are not initialised.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

hw/tpm/tpm_emulator.c

@@ -166,6 +166,7 @@ static int tpm_emulator_set_locality(TPMEmulator *tpm_emu, uint8_t locty_number,
 
     trace_tpm_emulator_set_locality(locty_number);
 
+    memset(&loc, 0, sizeof(loc));
     loc.u.req.loc = locty_number;
     if (tpm_emulator_ctrlcmd(tpm_emu, CMD_SET_LOCALITY, &loc,
                              sizeof(loc), sizeof(loc)) < 0) {