UPSTREAM: drm/i915/dp: Fix DSC line buffer depth programming

Fix the calculation of the DSC line buffer depth. This is limited both
by the source's and sink's maximum line buffer depth, but the former one
was not taken into account. On all Intel platform's the source's maximum
buffer depth is 13, so the overall limit is simply the minimum of the
source/sink's limit, regardless of the DSC version.

This leaves the DSI DSC line buffer depth calculation as-is, trusting
VBT.

On DSC version 1.2 for sinks reporting a maximum line buffer depth of 16
the line buffer depth was incorrectly programmed as 0, leading to a
corruption in color gradients / lines on the decompressed screen image.

Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Manasi Navare <navaremanasi@chromium.org>
Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240416221010.376865-2-imre.deak@intel.com


(cherry picked from commit f1d6aec4)

BUG=b:332903004, b:322223603
TEST=Verify Dell U3224KB 6k mode on Rex using UHBR, MST encoder, Big
     Joiner, and DSC

Change-Id: I50a3e4059a2e498c60cd29a180d8b6099ee52365
Signed-off-by: Rakshith M O <rakshith.m.o@intel.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/5802882


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