f2fs: fix to unlock folio in f2fs_read_data_large_folio()

f2fs: fix to unlock folio in f2fs_read_data_large_folio()

We missed to unlock folio in error path of f2fs_read_data_large_folio(),
fix it.

With below testcase, it can reproduce the bug.

touch /mnt/f2fs/file
truncate -s $((1024*1024*1024)) /mnt/f2fs/file
f2fs_io setflags immutable /mnt/f2fs/file
sync
echo 3 > /proc/sys/vm/drop_caches
time dd if=/mnt/f2fs/file of=/dev/null bs=1M count=1024
f2fs_io clearflags immutable /mnt/f2fs/file
echo 1 > /proc/sys/vm/drop_caches
time dd if=/mnt/f2fs/file of=/dev/null bs=1M count=1024
time dd if=/mnt/f2fs/file of=/dev/null bs=1M count=1024

Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>