libata: bugfix: Remove __le32 in ata_tf_to_fis()

The endianness attribute on the 'aux' local variable is wrong, and can
lead to wrong endianness on big-endian machines,

Signed-off-by: Marc Carino <marc.ceeeee@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>