spi: spi-fsl-dspi: Fix copy-paste error in dspi_probe

It seems that the proper structure field to use in this particular
case is *regmap_pushr* instead of regmap.

Addresses-Coverity-ID: 1470126 ("Copy-paste error")
Fixes: 58ba07e ("spi: spi-fsl-dspi: Add support for XSPI mode registers")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Acked-by: Esben Haabendal <eha@deif.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-fsl-dspi.c

@@ -1066,7 +1066,7 @@ static int dspi_probe(struct platform_device *pdev)
 			dev_err(&pdev->dev,
 				"failed to init pushr regmap: %ld\n",
 				PTR_ERR(dspi->regmap_pushr));
-			ret = PTR_ERR(dspi->regmap);
+			ret = PTR_ERR(dspi->regmap_pushr);
 			goto out_master_put;
 		}
 	}