drm/panel: Use drm_mode_duplicate()

Replace the hand rolled drm_mode_duplicate() with the
real thing.

@is_dup@
@@
drm_mode_duplicate(...)
{ ... }

@depends on !is_dup@
expression dev, oldmode;
identifier newmode;
@@
- newmode = drm_mode_create(dev);
+ newmode = drm_mode_duplicate(dev, oldmode);
  ...
- drm_mode_copy(newmode, oldmode);

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220218100403.7028-21-ville.syrjala@linux.intel.com


Acked-by: Sam Ravnborg <sam@ravnborg.org>