drm/dp: drop the size parameter from drm_dp_vsc_sdp_pack()

Currently the size parameter of drm_dp_vsc_sdp_pack() is always
the size of struct dp_sdp. Hence lets drop this parameter and
use sizeof() directly.

Suggested-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Acked-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240220195348.1270854-2-quic_abhinavk@quicinc.com