drm/i915: convert remaining intel_dp_vsc_sdp_pack

Commit 47f419e0 ("drm/dp: move intel_dp_vsc_sdp_pack() to generic helper")
and commit b55b88d8 ("drm/dp: drop the size parameter from drm_dp_vsc_sdp_pack()")
were based on top of a tree containing the
commit 31a5b6ed ("drm/i915/display: Unify VSC SPD preparation") but
landed in a tree where this commit didn't exist, leaving behind a spurious
case calling for a removed function: intel_dp_vsc_sdp_pack()

Let's convert the remaining case here so we can port this patch to
any tree that doesn't contain
commit 31a5b6ed ("drm/i915/display: Unify VSC SPD preparation")

In in kind of merge where this commit does exist, this line here will
be gone anyway and not needed any longer.

Fixes: 47f419e0 ("drm/dp: move intel_dp_vsc_sdp_pack() to generic helper")
Cc: Dave Airlie <airlied@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Abhinav Kumar <quic_abhinavk@quicinc.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240223191548.392185-1-rodrigo.vivi@intel.com