Fix missing tCycle/modfreq calculation.

Signed-off-by: John Traill <john.traill@freescale.com>
diff --git a/cpu/mpc86xx/spd_sdram.c b/cpu/mpc86xx/spd_sdram.c
index 44b0d41..39da3cc 100644
--- a/cpu/mpc86xx/spd_sdram.c
+++ b/cpu/mpc86xx/spd_sdram.c
@@ -466,6 +466,8 @@
 	 * are slower than the DDR module.
 	 */
 	busfreq = get_bus_freq(0) / 1000000;	/* MHz */
+	tCycle_ps = convert_bcd_tenths_to_cycle_time_ps(spd.clk_cycle3);
+	modfreq = 2 * 1000 * 1000 / tCycle_ps;
 
 	if ((spd.mem_type == SPD_MEMTYPE_DDR2) && (busfreq < 266)) {
 		printf("DDR: platform frequency too low for correct DDR2 controller operation\n");