drm: Use state helper instead of CRTC state pointer

Many drivers reference the crtc->pointer in order to get the current CRTC
state in their atomic_begin or atomic_flush hooks, which would be the new
CRTC state in the global atomic state since _swap_state happened when those
hooks are run.

Use the drm_atomic_get_new_crtc_state helper to get that state to make it
more obvious.

This was made using the coccinelle script below:

@ crtc_atomic_func @
identifier helpers;
identifier func;
@@

(
static struct drm_crtc_helper_funcs helpers = {
	...,
	.atomic_begin = func,
	...,
};
|
static struct drm_crtc_helper_funcs helpers = {
	...,
	.atomic_flush = func,
	...,
};
)

@@
identifier crtc_atomic_func.func;
identifier crtc, state;
symbol crtc_state;
expression e;
@@

  func(struct drm_crtc *crtc, struct drm_atomic_state *state) {
  ...
- struct tegra_dc_state *crtc_state = e;
+ struct tegra_dc_state *dc_state = e;
  <+...
-       crtc_state
+	dc_state
  ...+>
  }

@@
identifier crtc_atomic_func.func;
identifier crtc, state;
symbol crtc_state;
expression e;
@@

  func(struct drm_crtc *crtc, struct drm_atomic_state *state) {
  ...
- struct mtk_crtc_state *crtc_state = e;
+ struct mtk_crtc_state *mtk_crtc_state = e;
  <+...
-       crtc_state
+	mtk_crtc_state
  ...+>
  }

@ replaces_new_state @
identifier crtc_atomic_func.func;
identifier crtc, state, crtc_state;
@@

  func(struct drm_crtc *crtc, struct drm_atomic_state *state) {
  ...
- struct drm_crtc_state *crtc_state = crtc->state;
+ struct drm_crtc_state *crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
  ...
 }

@@
identifier crtc_atomic_func.func;
identifier crtc, state, crtc_state;
@@

  func(struct drm_crtc *crtc, struct drm_atomic_state *state) {
  struct drm_crtc_state *crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
  ...
- crtc->state
+ crtc_state
  ...
 }

@ adds_new_state @
identifier crtc_atomic_func.func;
identifier crtc, state;
@@

  func(struct drm_crtc *crtc, struct drm_atomic_state *state) {
+ struct drm_crtc_state *crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
  ...
- crtc->state
+ crtc_state
  ...
 }

@ include depends on adds_new_state || replaces_new_state @
@@

 #include <drm/drm_atomic.h>

@ no_include depends on !include && (adds_new_state || replaces_new_state) @
@@

+ #include <drm/drm_atomic.h>
  #include <drm/...>

Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: "James (Qian) Wang" <james.qian.wang@arm.com>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Mihail Atanassov <mihail.atanassov@arm.com>
Cc: Brian Starkey <brian.starkey@arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Paul Cercueil <paul@crapouillou.net>
Cc: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Sandy Huang <hjc@rock-chips.com>
Cc: "Heiko Stübner" <heiko@sntech.de>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201105164518.392891-1-maxime@cerno.tech