Revert "nb/amd/mct_ddr3: Enable DIMM parity when RDIMMs installed"

This reverts commit f961becc43.

On studying the BKDG more closely this is not the correct place
to enable DIMM parity.  Further patches to clarify the parity
setup process on Family 15h are forthcoming.

Change-Id: I5a3a4f1621e3048f9dfc159709410be9de6ebecd
Reviewed-on: https://review.coreboot.org/14271
Tested-by: build bot (Jenkins)
Tested-by: Raptor Engineering Automated Test Stand <noreply@raptorengineeringinc.com>
Reviewed-by: Martin Roth <martinroth@google.com>

src/northbridge/amd/amdmct/mct_ddr3/mct_d.c

@@ -5152,7 +5152,9 @@ static u8 AutoConfig_D(struct MCTStatStruc *pMCTstat,
 
 	if (Status & (1 << SB_Registered)) {
 		/* Registered DIMMs */
-		DramConfigLo |= 1 << ParEn;
+		if (!is_fam15h()) {
+			DramConfigLo |= 1 << ParEn;
+		}
 	} else {
 		/* Unbuffered DIMMs */
 		DramConfigLo |= 1 << UnBuffDimm;