spi: atmel-quadspi: (workaround) Always use DMA on sama7g5

Bus errors were seen when using mmiocpy with a flavor of mx66lm1g45g.
Set the DMA treshold to zero so that we always use DMA for data transfers.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>

Author: ambarus

drivers/spi/atmel-quadspi.c

@@ -230,7 +230,7 @@
 #define QSPI_CALIB_TIME			2000	/* 2 us */
 
 /* Use PIO for small transfers. */
-#define ATMEL_QSPI_DMA_MIN_BYTES	16
+#define ATMEL_QSPI_DMA_MIN_BYTES	0
 /**
  * struct atmel_qspi_pcal - Pad Calibration Clock Division
  * @pclk_rate: peripheral clock rate.