spi: cadence_qspi: Ensure check for max frequency in place

Ensure the intended SCLK frequency not exceeding the maximum
frequency. If that happen, SCLK will set to maximum frequency.

Signed-off-by: Chin Liang See <clsee@altera.com>
Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
Cc: Dinh Nguyen <dinh.linux@gmail.com>
Cc: Marek Vasut <marex@denx.de>
Cc: Stefan Roese <sr@denx.de>
Cc: Vikas Manocha <vikas.manocha@st.com>
Cc: Jagannadh Teki <jteki@openedev.com>
Cc: Pavel Machek <pavel@denx.de>
Acked-by: Pavel Machek <pavel@denx.de>

drivers/spi/cadence_qspi.c

@@ -122,6 +122,9 @@ static int cadence_spi_set_speed(struct udevice *bus, uint hz)
 	struct cadence_spi_priv *priv = dev_get_priv(bus);
 	int err;
 
+	if (hz > plat->max_hz)
+		hz = plat->max_hz;
+
 	/* Disable QSPI */
 	cadence_qspi_apb_controller_disable(priv->regbase);