spi: fsl-espi: improve check for SPI_QE_CPU_MODE

SPI_QE_CPU_MODE doesn't exist for ESPI and is set by of_mpc8xxx_spi_probe
based on DT property "mode". This property is not defined for ESPI,
see Documentation/devicetree/bindings/spi/fsl-spi.txt.
So print an error message and bail out if SPI_QE_CPU_MODE is set.
Signed-off-by: NHeiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: NMark Brown <broonie@kernel.org>

drivers/spi/spi-fsl-espi.c

@@ -583,8 +583,9 @@ static int fsl_espi_probe(struct device *dev, struct resource *mem,
 		goto err_probe;
 
 	if (mpc8xxx_spi->flags & SPI_QE_CPU_MODE) {
-		mpc8xxx_spi->rx_shift = 16;
-		mpc8xxx_spi->tx_shift = 24;
+		dev_err(dev, "SPI_QE_CPU_MODE is not supported on ESPI!\n");
+		ret = -EINVAL;
+		goto err_probe;
 	}
 
 	/* SPI controller initializations */