target: create and use target_name()

Several of the sites now using target_type_name() really
ought to be using an instance-specific name.  Create a
function called target_name(), accessing the instance's
own (command) name.

Use it in several places that really should be displaying
instance-specific names.  Also in several places which
were already doing so, but which had no wrapper to call.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

src/target/etm.c

@@ -1374,7 +1374,8 @@ COMMAND_HANDLER(handle_etm_config_command)
 	arm = target_to_arm(target);
 	if (!is_arm(arm)) {
 		command_print(CMD_CTX, "target '%s' is '%s'; not an ARM",
-				target->cmd_name, target_type_name(target));
+				target_name(target),
+				target_type_name(target));
 		return ERROR_FAIL;
 	}