tegra: spi: Wait a little after setting the clocks

For devices that need a delay between SPI transactions we seem to need an
additional delay before the first one if the CPU is running at full speed.
Add this, under control of the existing setting. At present it will only
be enabled with the Chrome OS EC.
Signed-off-by: NSimon Glass <sjg@chromium.org>

drivers/spi/tegra114_spi.c

@@ -152,6 +152,7 @@ static int tegra114_spi_probe(struct udevice *bus)
 			       bus->name, priv->freq, rate);
 		}
 	}
+	udelay(plat->deactivate_delay_us);
 
 	/* Clear stale status here */
 	setbits_le32(&regs->fifo_status,