spi: fsl-dspi: remove useless code for dspi driver.

Since we are using regmap framework's internal locks, so the
lock_arg for dspi_regmap_config is redundant here.

This patch just remove it, and then the dspi_regmap_config could
be const type.

Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-fsl-dspi.c

@@ -438,7 +438,7 @@ static int dspi_resume(struct device *dev)
 
 static SIMPLE_DEV_PM_OPS(dspi_pm, dspi_suspend, dspi_resume);
 
-static struct regmap_config dspi_regmap_config = {
+static const struct regmap_config dspi_regmap_config = {
 	.reg_bits = 32,
 	.val_bits = 32,
 	.reg_stride = 4,
@@ -492,7 +492,6 @@ static int dspi_probe(struct platform_device *pdev)
 		goto out_master_put;
 	}
 
-	dspi_regmap_config.lock_arg = dspi;
 	dspi->regmap = devm_regmap_init_mmio_clk(&pdev->dev, "dspi", base,
 						&dspi_regmap_config);
 	if (IS_ERR(dspi->regmap)) {