Btrfs: use the correct struct for BTRFS_IOC_LOGICAL_INO

BTRFS_IOC_LOGICAL_INO takes a btrfs_ioctl_logical_ino_args as argument,
not a btrfs_ioctl_ino_path_args. The lines were probably copy/pasted
when the code was written.

Since btrfs_ioctl_logical_ino_args and btrfs_ioctl_ino_path_args have
the same size, the actual IOCTL definition here does not change.

But, it makes the code less confusing for the reader.

Signed-off-by: Hans van Kranenburg <hans.van.kranenburg@mendix.com>
Signed-off-by: David Sterba <dsterba@suse.com>