tty: st-asc: Update tty alias

Since dtc v1.4.6-9-gaadd0b65c987, aliases property name
must include only lowercase and '-'.

After having updated all STi boards serial aliases from "ttyASN"
to "serialN", st-asc driver need to be updated accordingly as tty
aliases id is retrieved using of_alias_get_id().
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/st-asc.c

@@ -782,7 +782,9 @@ static struct asc_port *asc_of_get_asc_port(struct platform_device *pdev)
 	if (!np)
 		return NULL;
 
-	id = of_alias_get_id(np, ASC_SERIAL_NAME);
+	id = of_alias_get_id(np, "serial");
+	if (id < 0)
+		id = of_alias_get_id(np, ASC_SERIAL_NAME);
 
 	if (id < 0)
 		id = 0;