spi: Remove check for controller idling in spi sync path

Now that the idling flag is wholly behind the io_mutex, this broken piece
of code can be safely removed.

Signed-off-by: David Jander <david@protonic.nl>
Link: https://lore.kernel.org/r/20220621061234.3626638-6-david@protonic.nl
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi.c

@@ -3964,10 +3964,6 @@ static void __spi_transfer_message_noqueue(struct spi_controller *ctlr, struct s
 
 	mutex_lock(&ctlr->io_mutex);
 
-	/* If another context is idling the device then wait */
-	while (ctlr->idling)
-		usleep_range(10000, 11000);
-
 	was_busy = READ_ONCE(ctlr->busy);
 
 	ret = __spi_pump_transfer_message(ctlr, msg, was_busy);