[5.4] f2fs: fix to avoid memory leakage in f2fs_listxattr

[Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx>]

Please pick:

commit 688078e7f36c293dae25b338ddc9e0a2790f6e06
Author: Randall Huang <huangrandall@xxxxxxxxxx>
Date:   Fri Oct 18 14:56:22 2019 +0800

    f2fs: fix to avoid memory leakage in f2fs_listxattr

for the 5.4-stable branch.  It's also needed for earlier branches, but
needs adjustment so I will send a backport later.

Ben.

-- 
Ben Hutchings, Software Developer                         Codethink Ltd
https://www.codethink.co.uk/                 Dale House, 35 Dale Street
                                     Manchester, M1 2HF, United Kingdom