spi: altera: Fix memory leak on error path

Release master that have been previously allocated if the number of
chipselect is invalid.

Fixes: 8e04187 ("spi: altera: add SPI core parameters support via platform data.")
Signed-off-by: Pan Bian <bianpan2016@163.com>
Reviewed-by: Tom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20210120082635.49304-1-bianpan2016@163.com
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-altera.c

@@ -254,7 +254,8 @@ static int altera_spi_probe(struct platform_device *pdev)
 			dev_err(&pdev->dev,
 				"Invalid number of chipselect: %hu\n",
 				pdata->num_chipselect);
-			return -EINVAL;
+			err = -EINVAL;
+			goto exit;
 		}
 
 		master->num_chipselect = pdata->num_chipselect;