Despite the UPD comments the Chx_RankEnable fields are a bit mask which indicates which ranks are enabled for physical channel. Add the ability to set the rank mask correctly for dual rank LPDDR4 modules. BUG=chrome-os-partner:55446 Change-Id: I9dbed7bb6a4b512e57f6b4481180932a7cce91ff Signed-off-by: Aaron Durbin <adurbin@chromium.org> Reviewed-on: https://review.coreboot.org/15771 Tested-by: build bot (Jenkins) Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net> Reviewed-by: Furquan Shaikh <furquan@google.com> Reviewed-by: Andrey Petrov <andrey.petrov@intel.com> Reviewed-by: Duncan Laurie <dlaurie@chromium.org>