spi: rockchip: Signal unfinished DMA transfers

spi: rockchip: Signal unfinished DMA transfers

commit 4dc0dd83603f05dc3ae152af33ecb15104c313f3 upstream.

When using DMA, the transfer_one callback should return 1 because the
transfer hasn't finished yet.

A previous commit changed the function to return 0 when the DMA channels
were correctly prepared.

This manifested in Veyron boards with this message:

[ 1.983605] cros-ec-spi spi0.0: EC failed to respond in time

Fixes: ea9849113343 ("spi: rockchip: check return value of dmaengine_prep_slave_sg")
Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>