Use VPD variable "fsp_dimm_freq" to select DDR frequency limit.
Tested=On OCP Delta Lake, DDR frequency limit can be changed via VPD.
Signed-off-by: Tim Chu <Tim.Chu@quantatw.com>
Change-Id: I1232feae5090420d8fa42596b46f2d4dcaf9d635
Reviewed-on: https://review.coreboot.org/c/coreboot/+/48946
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Jonathan Zhang <jonzhang@fb.com>
58e1e0aee9