f2fs: handle dqget error in f2fs_transfer_project_quota()

We should set the error code when dqget() failed.

Fixes: 2c1d0305

 ("f2fs: support F2FS_IOC_FS{GET,SET}XATTR")
Signed-off-by: Yangtao Li <frank.li@vivo.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>