btrfs: rename btrfs_ioctl_same_args->total_files to dest_count

This makes the meaning of that struct member clear.

Signed-off-by: Mark Fasheh <mfasheh@suse.de>
btrfs: remove btrfs_ioctl_same_args->files_deduped

The name didn't make sense, I found limited usefulness for this data in
userspace and the semantics of when this would be incrememnted were unclear
(we would only increment on a fully sucessful dedupe, not on partial
dedupes). Better to just reclaim the space as reserved for now.

Signed-off-by: Mark Fasheh <mfasheh@suse.de>