ide: don't set PIO mode on pre-EIDE drives

Fix handling of the PIO modes for the pre-EIDE drives that did not support
the PIO Flow Control Transfer Mode value (00001 nnn) of the Set Transfer Mode
feature by skipping the actual mode programming.

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