qibfs: fix _another_ leak

failure to allocate inode => leaked dentry...

this one had been there since the initial merge; to be fair,
if we are that far OOM, the odds of failing at that particular
allocation are low...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

drivers/infiniband/hw/qib/qib_fs.c

@@ -55,6 +55,7 @@ static int qibfs_mknod(struct inode *dir, struct dentry *dentry,
 	struct inode *inode = new_inode(dir->i_sb);
 
 	if (!inode) {
+		dput(dentry);
 		error = -EPERM;
 		goto bail;
 	}