drm/i915/display: rename IS_DISPLAY_IP_STEP() to IS_DISPLAY_VER_STEP()

Unify macro naming on VER.

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Acked-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/6861e02f3adf15d56e89890000eb195070c33c9b.1724180287.git.jani.nikula@intel.com


Signed-off-by: Jani Nikula <jani.nikula@intel.com>