spi: rb4xx: Fix set_cs logic.

As it turns out, the set_cs() enable parameter refers to the logic level
on the CS pin, not the state of chip selection.

This broke functionality of the LEDs behind the CPLD, or at least delayed
the commands until another one came in to toggle CS.
Signed-off-by: Bert Vermeulen <bert@biot.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-rb4xx.c

@@ -90,7 +90,7 @@ static void rb4xx_set_cs(struct spi_device *spi, bool enable)
 	 * since it's all on the same hardware register. However the
 	 * CPLD needs CS deselected after every command.
 	 */
-	if (!enable)
+	if (enable)
 		rb4xx_write(rbspi, AR71XX_SPI_REG_IOC,
 			    AR71XX_SPI_IOC_CS0 | AR71XX_SPI_IOC_CS1);
 }