spi: fsl-espi: add missing static declaration to fsl_espi_cpu_irq

Add missing static declaration to fsl_espi_cpu_irq.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-fsl-espi.c

@@ -471,7 +471,7 @@ static void fsl_espi_cleanup(struct spi_device *spi)
 	spi_set_ctldata(spi, NULL);
 }
 
-void fsl_espi_cpu_irq(struct mpc8xxx_spi *mspi, u32 events)
+static void fsl_espi_cpu_irq(struct mpc8xxx_spi *mspi, u32 events)
 {
 	struct fsl_espi_reg *reg_base = mspi->reg_base;