ppc4xx: Add freqUART to CPU speed detection

This value is needed later for the device tree configuration of
the uart clock.

Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/cpu/ppc4xx/fdt.c b/cpu/ppc4xx/fdt.c
index 2acb250..44e95a5 100644
--- a/cpu/ppc4xx/fdt.c
+++ b/cpu/ppc4xx/fdt.c
@@ -79,10 +79,17 @@
 {
 	int rc;
 	u32 val;
+	PPC4xx_SYS_INFO sys_info;
+
+	get_sys_info(&sys_info);
 
 	debug("Updating node UART%d\n", i);
 
+#if defined(CFG_EXT_SERIAL_CLOCK)
 	val = cpu_to_fdt32(CFG_EXT_SERIAL_CLOCK);
+#else
+	val = cpu_to_fdt32(sys_info.freqUART);
+#endif
 	rc = fdt_setprop(fdt, offset, "clock-frequency", &val, 4);
 	if (rc)
 		printf("Unable to update node UART, err=%s\n", fdt_strerror(rc));