Backport short cables support from pata_ali.c and while at it cleanup
existing cable detection code.

This patch should allow UDMA > 2 modes on HP Pavilion N5430 and Fujitsu P2000.
Signed-off-by: NBartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Acked-by: NSergei Shtylyov <sshtylyov@ru.mvista.com>