mpc83xx: Suppress the warning 'burstlen'

suppress the warning 'burstlen' of spd_sdram.

Signed-off-by: Dave Liu <daveliu@freescale.com>
diff --git a/cpu/mpc83xx/spd_sdram.c b/cpu/mpc83xx/spd_sdram.c
index 2c17cee..54f0c83 100644
--- a/cpu/mpc83xx/spd_sdram.c
+++ b/cpu/mpc83xx/spd_sdram.c
@@ -576,7 +576,7 @@
 	if (spd.dataw_lsb == 0x20) {
 		if (spd.mem_type == SPD_MEMTYPE_DDR)
 			burstlen = 0x03; /* 32 bit data bus, burst len is 8 */
-		if (spd.mem_type == SPD_MEMTYPE_DDR2)
+		else
 			burstlen = 0x02; /* 32 bit data bus, burst len is 4 */
 		printf("\n   DDR DIMM: data bus width is 32 bit");
 	} else {