ide: move some bits from ide-timing.h to <linux/ide.h>

Move struct ide_timing and IDE_TIMING_* defines to <linux/ide.h>
from drivers/ide/ide-timing.h.

While at it:

- use u8/u16 instead of short for struct ide_timing fields

- use enum for IDE_TIMING_*

There should be no functional changes caused by this patch.

Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>