* Move xfer mode tuning code to ide-xfer-mode.c.
* Add CONFIG_IDE_XFER_MODE config option to be selected by host drivers
that support xfer mode tuning.
* Add CONFIG_IDE_XFER_MODE=n static inline versions of ide_set_pio()
and ide_set_xfer_rate().
* Make IDE_TIMINGS and BLK_DEV_IDEDMA config options select IDE_XFER_MODE,
also add explicit selects for few host drivers that need it.
* Build/link ide-xfer-mode.o and ide-pio-blacklist.o (it is needed only
by ide-xfer-mode.o) only if CONFIG_IDE_XFER_MODE=y.
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>