drivers: serial: uart_native_posix: Replace use of DT_INST_LABEL

As we work to phase out devicetree 'label properties, convert
driver to just use dev->name instead of DT_INST_LABEL.

Signed-off-by: Kumar Gala <galak@kernel.org>
diff --git a/drivers/serial/uart_native_posix.c b/drivers/serial/uart_native_posix.c
index 841a95f..e6b1c1d 100644
--- a/drivers/serial/uart_native_posix.c
+++ b/drivers/serial/uart_native_posix.c
@@ -218,8 +218,7 @@
 	d = (struct native_uart_status *)dev->data;
 
 	if (IS_ENABLED(CONFIG_NATIVE_UART_0_ON_OWN_PTY)) {
-		int tty_fn = open_tty(d, DT_INST_LABEL(0),
-				      auto_attach);
+		int tty_fn = open_tty(d, dev->name, auto_attach);
 
 		d->in_fd = tty_fn;
 		d->out_fd = tty_fn;
@@ -255,7 +254,7 @@
 
 	d = (struct native_uart_status *)dev->data;
 
-	tty_fn = open_tty(d, DT_INST_LABEL(1), false);
+	tty_fn = open_tty(d, dev->name, false);
 
 	d->in_fd = tty_fn;
 	d->out_fd = tty_fn;