ata: move sata_deb_timing_*() to libata-sata.c

* move sata_deb_timing_*() to libata-sata.c

* add static inline for sata_ehc_deb_timing() for
  CONFIG_SATA_HOST=n case

Code size savings on m68k arch using (modified) atari_defconfig:

   text    data     bss     dec     hex filename
before:
  32158     572      40   32770    8002 drivers/ata/libata-core.o
after:
  32015     572      40   32627    7f73 drivers/ata/libata-core.o

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