[BUG]
During fuzz/007 we hit the following error:
------
====== RUN MAYFAIL /home/adam/btrfs/btrfs-progs/btrfs rescue super-recover -y -v /home/adam/btrfs/btrfs-progs/tests//fuzz-tests/images/bko-200409.raw.restored.scratch
ERROR: tree_root block unaligned: 33554431
ERROR: superblock checksum matches but it has invalid members
ERROR: tree_root block unaligned: 33554431
ERROR: superblock checksum matches but it has invalid members
ERROR: tree_root block unaligned: 33554431
ERROR: superblock checksum matches but it has invalid members
ERROR: failed to add chunk map start=12582912 len=8454144: -17 (File exists)
Couldn't read chunk tree
failed (ignored, ret=139): /home/adam/btrfs/btrfs-progs/btrfs rescue super-recover -y -v /home/adam/btrfs/btrfs-progs/tests//fuzz-tests/images/bko-200409.raw.restored.scratch
mayfail: returned code 139 (SEGFAULT), not ignored
test failed for case 007-simple-super-recover
------

[CAUSE]
In __open_ctree_fd(), if we have valid @open_ctree_flags and
btrfs_scan_fs_devices() successes without problem, no matter what
happens we will call btrfs_close_devices(), thus free all related
devices.

In super-recover, before we call open_ctree(), we have called
btrfs_scan_fs_devices() already, so btrfs_scan_fs_devices() should not
fail in open_ctree(), fs_devices will always be freed in open_ctree() or
close_ctree().

[FIX]
So in super-recover.c, we should not call btrfs_close_devices(), or we
will find fs_devices->list get poisoned, and trigger segfault when
exiting.

Signed-off-by: Qu Wenruo <wqu@suse.com>