UPSTREAM: drm/i915/dp: Fix the PSR debugfs entries wrt. MST connectors

MST connectors don't have a static attached encoder, as their encoder
can change depending on the pipe they use; so the encoder for an MST
connector can't be retrieved using intel_dp_attached_encoder() (which
may return NULL for MST). Most of the PSR debugfs entries depend on a
static connector -> encoder mapping which is only true for eDP and SST
DP connectors and not for MST. These debugfs entries were enabled for
MST connectors as well recently to provide PR information for them, but
handling MST connectors needs more changes.

Fix this by not adding for now the PSR entries on MST connectors. To
make things more uniform add the entries for SST connectors on all
platforms, not just on platforms supporting DP2.0.

v2:
- Keep adding the entries for SST connectors. (Jouni)
- Add a TODO: comment for MST support.

Fixes: ef75c25e ("drm/i915/panelreplay: Debugfs support for panel replay")
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/9850


Cc: Animesh Manna <animesh.manna@intel.com>
Cc: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240103152609.2434100-1-imre.deak@intel.com


(cherry picked from commit 9b0b61c5)

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

Change-Id: I9e38f0219c780237254906d7294031566c58800f
Signed-off-by: Rakshith M O <rakshith.m.o@intel.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/5802786


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