drm/i915: Use hw.active instead of uapi.active in the initial plane readout

drm/i915: Use hw.active instead of uapi.active in the initial plane readout

We're interested in the actual hardware state rather than the uapi
state, so grab the crtc active flag from the correct spot.

In practice the two will be identical here becase
.get_initial_plane_config() will reject the initial FB when
joiner is active.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patch.msgid.link/20251119181606.17129-5-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>