btrfs: adjust return type of btrfs_getxattr

The xattr_handler::get prototype returns int, use it. The only ssize_t
exception is the per-inode listxattr handler.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2 files changed