drivers: susbsys: Check errors on devices selected using dt macro

Some Kconfig defined devices may be defined using dt_chosen_label
function. Since there is no way to ensure a device enabled in dts
is also defined in Kconfig, it may happen that instance is not
actually defined.
In this case device_get_binding might return 0, leading to undefined
behavior in the function that calls it.
When not already done, systematically check return of function
device_get_binding on devices defined through dt_chosen_label macro.
Trigger ASSERT when required and return error when possible.

Fixes #20068

Signed-off-by: Erwan Gouriou <erwan.gouriou@linaro.org>

subsys/shell/shell_uart.c

@@ -274,6 +274,10 @@ static int enable_shell_uart(struct device *arg)
 		(CONFIG_SHELL_BACKEND_SERIAL_LOG_LEVEL > LOG_LEVEL_DBG) ?
 		CONFIG_LOG_MAX_LEVEL : CONFIG_SHELL_BACKEND_SERIAL_LOG_LEVEL;
 
+	if (dev == NULL) {
+		return -ENODEV;
+	}
+
 	shell_init(&shell_uart, dev, true, log_backend, level);
 
 	return 0;