UPSTREAM: drm/panelreplay: dpcd register definition for panelreplay

Add DPCD register definition for discovering, enabling and
checking status of panel replay of the sink.

Cc: Jouni Högander <jouni.hogander@intel.com>
Cc: Arun R Murthy <arun.r.murthy@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231108072303.3414118-2-animesh.manna@intel.com


(cherry picked from commit 48d054c2)

BUG=b:308455498
TEST=Verify Asus PG32UQXR 4K160 mode on Rex using Big Joiner

Change-Id: I72db8882d9997297a8f6fe98608189bb6d67dd57
Signed-off-by: Rakshith M O <rakshith.m.o@intel.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/5802778


Reviewed-by: Manasi Navare <navaremanasi@chromium.org>
Reviewed-by: Sean Paul <sean@poorly.run>
Signed-off-by: Hubert Mazur <hmazur@google.com>