[IA64] SGI SN drivers: don't report !sn2 hardware as an error

This stuff is all in the generic ia64 kernel, and the new initcall error
reporting complains about them.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/drivers/serial/sn_console.c b/drivers/serial/sn_console.c
index 43e67d6..60ea4a3 100644
--- a/drivers/serial/sn_console.c
+++ b/drivers/serial/sn_console.c
@@ -820,7 +820,7 @@
 	int retval;
 
 	if (!ia64_platform_is("sn2"))
-		return -ENODEV;
+		return 0;
 
 	printk(KERN_INFO "sn_console: Console driver init\n");