spi/ath79: add missing HIGH->LOW SCK transition

The 'ath79_spi_txrx_mode0' function does not
set the SCK signal to LOW at the end of a word
transfer. This causes communications errors with
certain devices (e.g. the PCF2123 RTC chip).

The patch ensures that the SCK signal will be LOW.
Signed-off-by: NGabor Juhos <juhosg@openwrt.org>
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>

drivers/spi/spi-ath79.c

@@ -200,6 +200,8 @@ static u32 ath79_spi_txrx_mode0(struct spi_device *spi, unsigned nsecs,
 		ath79_spi_delay(sp, nsecs);
 		ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out | AR71XX_SPI_IOC_CLK);
 		ath79_spi_delay(sp, nsecs);
+		if (bits == 1)
+			ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out);
 
 		word <<= 1;
 	}