spi/atmel: fix speed_hz check in atmel_spi_transfer()

atmel_spi_transfer() would check speed_hz and fail if
the speed was changed in the transfer. After commit
"spi: make sure all transfer has proper speed set"
this would happen on all transfers.

Change speed_hz check to only fail if a lower speed
than max is requested.
Signed-off-by: Joachim Eastwood <manabian@gmail.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

drivers/spi/spi-atmel.c

@@ -847,8 +847,8 @@ static int atmel_spi_transfer(struct spi_device *spi, struct spi_message *msg)
 		}
 
 		/* FIXME implement these protocol options!! */
-		if (xfer->speed_hz) {
-			dev_dbg(&spi->dev, "no protocol options yet\n");
+		if (xfer->speed_hz < spi->max_speed_hz) {
+			dev_dbg(&spi->dev, "can't change speed in transfer\n");
 			return -ENOPROTOOPT;
 		}