UPSTREAM: drm/i915: Remove DRM_MODE_FLAG_DBLSCAN checks from .mode_valid() hooks

We never set connector->doublescan_allowed, so the probe helper
already filters out all doublescan modes for us.

Sadly we still need to keep the explicit doublescan checks
in .compute_config as outlined in commit e4dd27aa
("drm/i915: Allow DBLSCAN user modes with eDP/LVDS/DSI")

Reviewed-by: Vandita Kulkarni <vandita.kulkarni@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240402135148.23011-2-ville.syrjala@linux.intel.com


(cherry picked from commit e00f20ba)

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

Change-Id: If4b1c447afe037eb6643185d4aaa309f59209340
Signed-off-by: Rakshith M O <rakshith.m.o@intel.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/5802852


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