ide: expiry() returns int, negative expiry() return values won't be noticed

bart:
It seems like the bug could cause insanely long timeouts for:
- ATA_DMA_ERR error in dma_timer_expiry()
- commands without ->expiry in tc86c001_timer_expiry()
  (TC86C001 IDE controller only)

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
[bart: port it to the current tree]
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>