oprofilefs_mkdir() doesn't need superblock argument

it's always equal to ->d_sb of the second argument (parent dentry),
due to either being literally that, or ->d_sb of parent's parent.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/drivers/oprofile/oprofile_perf.c b/drivers/oprofile/oprofile_perf.c
index 52ad942..923a245 100644
--- a/drivers/oprofile/oprofile_perf.c
+++ b/drivers/oprofile/oprofile_perf.c
@@ -147,7 +147,7 @@
 		char buf[4];
 
 		snprintf(buf, sizeof buf, "%d", i);
-		dir = oprofilefs_mkdir(root->d_sb, root, buf);
+		dir = oprofilefs_mkdir(root, buf);
 		oprofilefs_create_ulong(root->d_sb, dir, "enabled", &counter_config[i].enabled);
 		oprofilefs_create_ulong(root->d_sb, dir, "event", &counter_config[i].event);
 		oprofilefs_create_ulong(root->d_sb, dir, "count", &counter_config[i].count);