ata: sata_rescan must scan for block devices

ata: sata_rescan must scan for block devices

A system may have multiple SATA controller. Removing the controller with
the lowest sequence number before probing all SATA controllers makes no
sense.

In sata_rescan we remove all block devices which are children of SATA
controllers. We also have to remove the bootdev devices as they will be
created when scanning for block devices.

After probing all SATA controllers we must scan for block devices otherwise
we end up without any SATA block device.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Tony Dinh <mibodhi@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>