drm/tidss: crtc: Cleanup reset implementation

The tidss_crtc_reset() function will (rightfully) destroy any
pre-existing state.

However, the tidss CRTC driver has its own CRTC state structure that
subclasses drm_crtc_state, and yet will destroy the previous state
by calling __drm_atomic_helper_crtc_destroy_state() and kfree() on its
drm_crtc_state pointer.

It works only because the drm_crtc_state is the first field in the
structure, and thus its offset is 0. It's incredibly fragile however, so
let's call our destroy implementation in such a case to deal with it
properly.

Reviewed-by: Thomas Zimmermann <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Maxime Ripard <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/gpu/drm/tidss/tidss_crtc.c

···
 	struct tidss_crtc_state *tstate;
 
 	if (crtc->state)
-		__drm_atomic_helper_crtc_destroy_state(crtc->state);
-
-	kfree(crtc->state);
+		tidss_crtc_destroy_state(crtc, crtc->state);
 
 	tstate = kzalloc(sizeof(*tstate), GFP_KERNEL);
 	if (!tstate) {