haswell: Enable 2x Refresh mode

Send the PCODE mailbox command to enable 2x refresh mode if it
is not already enabled by MRC.

TEST=build and boot on peppy, check /sys/firmware/log for
successful report that 2x Refresh is enabled.  Ensure it is
also enabled after suspend/resume cycle.

Change-Id: I8473ace7302674eb79f537d431bc8bf84c4abeaa
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/240701
Reviewed-by: Shawn N <shawnn@chromium.org>
(cherry picked from commit 6b0827894d85556d7aa84cadd8c0f72311ab0716)
Reviewed-on: https://chromium-review.googlesource.com/252991
Commit-Queue: Steven Jian <steven.jian@intel.com>
Tested-by: Steven Jian <steven.jian@intel.com>
2 files changed