spi: atmel-quadspi: Disable the QSPI IP at suspend()

It is safer to disable the QSPI IP at suspend, in order to avoid
possible impact of glitches on the internal FSMs. This is a theoretical
fix, there were no problems seen as of now. Tested on sama5d2 and
sam9x60 versions of the IP.
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20210210135428.204134-1-tudor.ambarus@microchip.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/atmel-quadspi.c

@@ -657,6 +657,7 @@ static int __maybe_unused atmel_qspi_suspend(struct device *dev)
 	struct spi_controller *ctrl = dev_get_drvdata(dev);
 	struct atmel_qspi *aq = spi_controller_get_devdata(ctrl);
 
+	atmel_qspi_write(QSPI_CR_QSPIDIS, aq, QSPI_CR);
 	clk_disable_unprepare(aq->qspick);
 	clk_disable_unprepare(aq->pclk);