spi: cadence: revert "Add SPI transfer delays"

The commit 855a40cd ("spi: cadence: Add SPI transfer delays") adds a
delay after each transfer into the driver's transfer_one(). However,
the delay is already done in SPI core. So this commit unnecessarily
doubles the delay amount. Revert this commit.
Signed-off-by: Nam Cao <namcao@linutronix.de>
Link: https://lore.kernel.org/r/20231206145233.74982-1-namcao@linutronix.deSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-cadence.c

@@ -451,7 +451,6 @@ static int cdns_transfer_one(struct spi_controller *ctlr,
 		udelay(10);
 
 	cdns_spi_process_fifo(xspi, xspi->tx_fifo_depth, 0);
-	spi_transfer_delay_exec(transfer);
 
 	cdns_spi_write(xspi, CDNS_SPI_IER, CDNS_SPI_IXR_DEFAULT);
 	return transfer->len;