drm/i915/display: Use intel_crtc_destroy_state instead kfree

intel_encoder_current_mode() seems to leak some resource because
it uses kfree instead of intel_crtc_destroy_state let us fix that.

Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231010183101.704439-2-suraj.kandpal@intel.com