[POWERPC] bootwrapper: serial_console_init() fixes

1. Search the entire compatible list for serial devices.

The serial code previously did a simple strcmp on the compatible
node; this fails when the match string is not the first compatible
listed.  Use dt_is_compatible() instead.

2. Don't call serial_edit_cmdline if getc isn't defined.
Signed-off-by: Scott Wood <scottwood@freescale.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/boot/serial.c

@@ -114,18 +114,14 @@ int serial_console_init(void)
 {
 	void *devp;
 	int rc = -1;
-	char compat[MAX_PROP_LEN];
 
 	devp = serial_get_stdout_devp();
 	if (devp == NULL)
 		goto err_out;
 
-	if (getprop(devp, "compatible", compat, sizeof(compat)) < 0)
-		goto err_out;
-
-	if (!strcmp(compat, "ns16550"))
+	if (dt_is_compatible(devp, "ns16550"))
 		rc = ns16550_console_init(devp, &serial_cd);
-	else if (!strcmp(compat, "marvell,mpsc"))
+	else if (dt_is_compatible(devp, "marvell,mpsc"))
 		rc = mpsc_console_init(devp, &serial_cd);
 
 	/* Add other serial console driver calls here */
@@ -133,10 +129,12 @@ int serial_console_init(void)
 	if (!rc) {
 		console_ops.open = serial_open;
 		console_ops.write = serial_write;
-		console_ops.edit_cmdline = serial_edit_cmdline;
 		console_ops.close = serial_close;
 		console_ops.data = &serial_cd;
 
+		if (serial_cd.getc)
+			console_ops.edit_cmdline = serial_edit_cmdline;
+
 		return 0;
 	}
 err_out: