drm/msm/dp: Removed fixed nvid "support"

drm/msm/dp: Removed fixed nvid "support"

The "desc" member of struct dp_panel is zero-initialized during
allocation and never assigned, resulting in dp_ctrl_use_fixed_nvid()
never returning true. This returned boolean value is passed around but
never acted upon.

Perform constant propagation and remove the traces of "fixed nvid".

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/585344/
Link: https://lore.kernel.org/r/20240328-msm-dp-cleanup-v2-2-a5aed9798d32@quicinc.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>