hwsim tests: Silence chown warnings

If running in a VM with the logs going to a host filesystem
chown isn't actually possible, silence any warnings from it.

Signed-hostap: Johannes Berg <johannes.berg@intel.com>

tests/hwsim/start.sh

@@ -65,9 +65,9 @@ done
 sudo $VALGRIND_HAPD $HAPD -ddKt$TRACE -g /var/run/hostapd-global -G $GROUP -ddKt > $LOGDIR/hostapd &
 
 sleep 1
-sudo chown $USER $LOGDIR/hwsim0.dump
+sudo chown -f $USER $LOGDIR/hwsim0.dump
 if [ "x$VALGRIND" = "xy" ]; then
-    sudo chown $USER $LOGDIR/*valgrind*
+    sudo chown -f $USER $LOGDIR/*valgrind*
 fi
 
 if [ -x $HLR_AUC_GW ]; then