caif-spi: Bugfix SPI_DATA_POS settings were inverted.

The setting of SPI_DATA_POS depending on CONFIG_CAIF_SPI_SYNC
where inverted.

Signed-off-by: Sjur Braendeland <sjur.brandeland@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>