spi: atmel-quadspi: Disable clock in probe error path

If the call to of_device_get_match_data() fails on probe of the Atmel
QuadSPI driver, the clock "aq->pclk" is erroneously not unprepared and
disabled.  Fix it.

Fixes: 2e5c8888 ("spi: atmel-quadspi: add support for sam9x60 qspi controller")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: <stable@vger.kernel.org> # v5.1+
Cc: Tudor Ambarus <tudor.ambarus@microchip.com>
Cc: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/8f8dc2815aa97b2378528f08f923bf81e19611f0.1604874488.git.lukas@wunner.deSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/atmel-quadspi.c

@@ -594,7 +594,7 @@ static int atmel_qspi_probe(struct platform_device *pdev)
 	if (!aq->caps) {
 		dev_err(&pdev->dev, "Could not retrieve QSPI caps\n");
 		err = -EINVAL;
-		goto exit;
+		goto disable_pclk;
 	}
 
 	if (aq->caps->has_qspick) {