spi: Remove unneeded READ_ONCE for ctlr->busy flag

Now this flag is written entirely in the mutex, so no need for READ_ONCE
Signed-off-by: David Jander <david@protonic.nl>
Link: https://lore.kernel.org/r/20220621061234.3626638-9-david@protonic.nlSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi.c

@@ -3955,7 +3955,7 @@ static void __spi_transfer_message_noqueue(struct spi_controller *ctlr, struct s
 
 	mutex_lock(&ctlr->io_mutex);
 
-	was_busy = READ_ONCE(ctlr->busy);
+	was_busy = ctlr->busy;
 
 	ret = __spi_pump_transfer_message(ctlr, msg, was_busy);
 	if (ret)