[PATCH] libata: Fix a drive detection problem

The current code follows the spec but uses an overlong delay. This would
be great if the hardware did. Several vendors however forget the D7
pulldown. Fortunately 0xFF isnt a sane reset state so we can use it to
skip detection as is done in drivers/ide. (ie this is a tested solution
over a long time)

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>