sysfs: add unsigned long cast to prevent compile warning

"sysfs: use rb-tree for inode number lookup" added a new printk which
causes a new compile warning on s390 (and few other architectures):

fs/sysfs/dir.c: In function 'sysfs_link_sibling':
fs/sysfs/dir.c:63:4: warning: format '%lx' expects argument of type
  'long unsigned int', but argument 2 has type 'ino_t' [-Wform

Add an explicit unsigned long cast since ino_t is an unsigned long on
most architectures.

Cc: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

fs/sysfs/dir.c

@@ -60,7 +60,8 @@ static void sysfs_link_sibling(struct sysfs_dirent *sd)
 		} else if (sd->s_ino > node->s_ino) {
 			p = &node->inode_node.rb_right;
 		} else {
-			printk(KERN_CRIT "sysfs: inserting duplicate inode '%lx'\n", sd->s_ino);
+			printk(KERN_CRIT "sysfs: inserting duplicate inode '%lx'\n",
+			       (unsigned long) sd->s_ino);
 			BUG();
 		}
 #undef node