All sata based drivers are bind and corresponding block
device is created. Based on this find_scsi_device() is able
to get back block device based on scsi_curr_dev pointer.
intr_scsi() is commented now but it can be replaced by calling
find_scsi_device() and scsi_scan().
scsi_dev_desc[] is commented out but common/scsi.c heavily depends on
it. That's why CONFIG_SYS_SCSI_MAX_DEVICE is hardcoded to 1 and symbol
is reassigned to a block description allocated by uclass.
There is only one block description by device now but it doesn't need to
be correct when more devices are present.