spi: spi-mtk-nor: reject DTR ops

Double Transfer Rate (DTR) ops are added in spi-mem. But this controller
doesn't support DTR transactions. Since we don't use the default
supports_op(), which rejects all DTR ops, do that explicitly in our
supports_op().
Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20200623183030.26591-5-p.yadav@ti.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-mtk-nor.c

@@ -211,6 +211,12 @@ static bool mtk_nor_supports_op(struct spi_mem *mem,
 	if (op->cmd.buswidth != 1)
 		return false;
 
+	/* DTR ops not supported. */
+	if (op->cmd.dtr || op->addr.dtr || op->dummy.dtr || op->data.dtr)
+		return false;
+	if (op->cmd.nbytes != 1)
+		return false;
+
 	if ((op->addr.nbytes == 3) || (op->addr.nbytes == 4)) {
 		if ((op->data.dir == SPI_MEM_DATA_IN) && mtk_nor_match_read(op))
 			return true;