sata: fix sata_Probe return value check

sata_probe returns 1 for failure, so don't checkout for < 0

fixes: f19f1ecb dm: sata: Support driver model with the 'sata' command

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
Reviewed-by: Simon Glass <sjg@chromium.org>