drm/i915/display: Free crtc_state in verify_crtc_state

Free hw_crtc_state in verify_crtc_state after we are done using
this or else it's just a resource leak.

Fixes: 2745bdda ("drm/i915: Stop clobbering old crtc state during state check")
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231010053208.691260-1-suraj.kandpal@intel.com