nb/amd/mct_ddr3: Fix RDIMM training failure on Fam15h

Certain registered DIMMs failed training due to an error
likely introduced during historical rebase.  Ensure that
the SubMemclkRegDly bit is set according to BKDG
recommendations on Family 15 processors.

Change-Id: I24c95265dada9eabf4df280b6f2b4a1eb9cecaf1
Signed-off-by: Timothy Pearson <tpearson@raptorengineeringinc.com>
Reviewed-on: https://review.coreboot.org/13148
Tested-by: build bot (Jenkins)
Tested-by: Raptor Engineering Automated Test Stand <noreply@raptorengineeringinc.com>
Reviewed-by: Martin Roth <martinroth@google.com>
1 file changed