ata: allow subsystem to be used on m32r and s390 archs

Both archs should work just fine with libata subsystem nowadays.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Tejun Heo <tj@kernel.org>