FROMGIT: drm/i915/dp: Initialize the link parameters during HW readout

Initialize the DP link parameters during HW readout. These need to be
up-to-date at least for the MST topology probing, which depends on the
link rate and lane count programmed in DPCD. A follow-up patch will
program the DPCD values to reflect the maximum link parameters before
the first MST topology probing, but should do so only if the link is
disabled (link_trained==false).

Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240722165503.2084999-6-imre.deak@intel.com
(cherry picked from commit a3f91f40
 https://gitlab.freedesktop.org/drm/i915/kernel.git

 drm-intel-next)

BUG=b:332903004, b:322223603
TEST=Verify the link training fallback for UHBR<->non-UHBR rates

Change-Id: I929686aa23c84dd20db794fccf11caf52c8ec188
Signed-off-by: Rakshith M O <rakshith.m.o@intel.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/5802904


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