powerpc/mpc8xxx: check SPD length before using part number

Only use DDR DIMM part number if SPD has valid length, to prevent from
display garbage in case SPD doesn't cover these fields.

Signed-off-by: York Sun <yorksun@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/arch/powerpc/cpu/mpc8xxx/ddr/ddr3_dimm_params.c b/arch/powerpc/cpu/mpc8xxx/ddr/ddr3_dimm_params.c
index 756b15f..838cebe 100644
--- a/arch/powerpc/cpu/mpc8xxx/ddr/ddr3_dimm_params.c
+++ b/arch/powerpc/cpu/mpc8xxx/ddr/ddr3_dimm_params.c
@@ -114,7 +114,8 @@
 	 * and copying the part name in ASCII from the SPD onto it
 	 */
 	memset(pdimm->mpart, 0, sizeof(pdimm->mpart));
-	memcpy(pdimm->mpart, spd->mpart, sizeof(pdimm->mpart) - 1);
+	if ((spd->info_size_crc & 0xF) > 1)
+		memcpy(pdimm->mpart, spd->mpart, sizeof(pdimm->mpart) - 1);
 
 	/* DIMM organization parameters */
 	pdimm->n_ranks = ((spd->organization >> 3) & 0x7) + 1;