x86: prevent /sys/firmware/sgi_uv from being created on non-uv systems

/sys/firmware/sgi_uv should only be created on uv systems.
Signed-off-by: Russ Anderson <rja@sgi.com>
LKML-Reference: <20090403222423.GA28546@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/uv_sysfs.c

@@ -21,6 +21,7 @@
 
 #include <linux/sysdev.h>
 #include <asm/uv/bios.h>
+#include <asm/uv/uv.h>
 
 struct kobject *sgi_uv_kobj;
 
@@ -47,6 +48,9 @@ static int __init sgi_uv_sysfs_init(void)
 {
 	unsigned long ret;
 
+	if (!is_uv_system())
+		return -ENODEV;
+
 	if (!sgi_uv_kobj)
 		sgi_uv_kobj = kobject_create_and_add("sgi_uv", firmware_kobj);
 	if (!sgi_uv_kobj) {