dm: spi: soft_spi bug fix

When doing xfer, should use device->parent, but not device
When doing bit xfer, should use "!!(tmpdout & 0x80)", but not
"(tmpdout & 0x80)"

Signed-off-by: Peng Fan <van.freenix@gmail.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Jagan Teki <jteki@openedev.com>
Reviewed-by: Simon Glass <sjg@chromium.org>