ide-disk: extend timeout for PIO-in commands

s/WAIT_CMD/WAIT_WORSTCASE/ to make the timeout the same as in do_rw_taskfile()

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