Commit 1c11b63e ("btrfs: replace pending/pinned chunks lists with io
tree") introduced btrfs_device::alloc_state extent io tree, but it
doesn't initialize the fs_info and owner member.

This means the following features are not properly supported:

- Fs owner report for insert_state() error
  Without fs_info initialized, although btrfs_err() won't panic, it
  won't output which fs is causing the error.

- Wrong owner for trace events
  alloc_state will get the owner as pinned extents.

Fix this by assiging proper fs_info and owner for
btrfs_device::alloc_state.

Fixes: 1c11b63e ("btrfs: replace pending/pinned chunks lists with io tree")
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>