rockchip: rk3288: fix FREF_MIN_HZ constant

According to the TRM the minimum FREF frequency is 269kHz not MHz.
Adapt the constant accordingly.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Simon Glass <sjg@chromium.org>

drivers/clk/clk_rk3288.c

@@ -47,7 +47,7 @@ enum {
 	OUTPUT_MAX_HZ	= 2200U * 1000000,
 	OUTPUT_MIN_HZ	= 27500000,
 	FREF_MAX_HZ	= 2200U * 1000000,
-	FREF_MIN_HZ	= 269 * 1000000,
+	FREF_MIN_HZ	= 269 * 1000,
 };
 
 enum {