ata: fix CodingStyle issues in PATA timings code

* fix the overly long line in ata_timing_quantize()

* use standard kernel CodingStyle in ata_timing_merge()

* do not use assignment in if condition in ata_timing_compute()

* fix non-standard comment style in ata_timing_compute()

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>