ide_drive_t.sleeping field added.  0 in sleep field used to
indicate inactive sleeping but because 0 is a valid jiffy
value, though slim, there's a chance that something can go
weird.  And while at it, explicit jiffy comparisons are
converted to use time_before() macros.
Signed-off-by: Tejun Heo <tj@home-tj.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>