spi: make sure all transfer has proper speed set

When spi client does the spi transfer and if it does not set
the speed for each transfer then set it as default
of spi device in spi core before calling low level transfer.

This will remove the extra check in low level driver for setting
speed.
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

drivers/spi/spi.c

@@ -1369,12 +1369,14 @@ static int __spi_async(struct spi_device *spi, struct spi_message *message)
 	}
 
 	/**
-	 * Set transfer bits_per_word as spi device default if it is not
-	 * set for this transfer.
+	 * Set transfer bits_per_word and max speed as spi device default if
+	 * it is not set for this transfer.
 	 */
 	list_for_each_entry(xfer, &message->transfers, transfer_list) {
 		if (!xfer->bits_per_word)
 			xfer->bits_per_word = spi->bits_per_word;
+		if (!xfer->speed_hz)
+			xfer->speed_hz = spi->max_speed_hz;
 	}
 
 	message->spi = spi;