[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/char/mmtimer.c b/drivers/char/mmtimer.c
index c923781..1b05fa6 100644
--- a/drivers/char/mmtimer.c
+++ b/drivers/char/mmtimer.c
@@ -675,7 +675,7 @@
 	cnodeid_t node, maxn = -1;
 
 	if (!ia64_platform_is("sn2"))
-		return -1;
+		return 0;
 
 	/*
 	 * Sanity check the cycles/sec variable