drm/i915: annotate maybe unused but set intel_plane_state variables

Prepare for re-enabling -Wunused-but-set-variable.

for_each_new_intel_plane_in_state() requires passing in a struct
intel_plane_state pointer, which it uses, but in many places this leads
to warning about unused but set variables. Annotate them with
__maybe_unused.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/438ff3b257b7f85ecca5750ae8687336faee0a79.1685119007.git.jani.nikula@intel.com

drivers/gpu/drm/i915/display/intel_atomic_plane.c

@@ -722,7 +722,7 @@ skl_next_plane_to_commit(struct intel_atomic_state *state,
 {
 	struct intel_crtc_state *crtc_state =
 		intel_atomic_get_new_crtc_state(state, crtc);
-	struct intel_plane_state *plane_state;
+	struct intel_plane_state __maybe_unused *plane_state;
 	struct intel_plane *plane;
 	int i;
 

drivers/gpu/drm/i915/display/intel_cdclk.c

@@ -2959,7 +2959,7 @@ int intel_cdclk_atomic_check(struct intel_atomic_state *state,
 {
 	const struct intel_cdclk_state *old_cdclk_state;
 	const struct intel_cdclk_state *new_cdclk_state;
-	struct intel_plane_state *plane_state;
+	struct intel_plane_state __maybe_unused *plane_state;
 	struct intel_plane *plane;
 	int ret;
 	int i;

drivers/gpu/drm/i915/display/intel_display.c

@@ -971,7 +971,7 @@ static void intel_crtc_enable_flip_done(struct intel_atomic_state *state,
 	const struct intel_crtc_state *crtc_state =
 		intel_atomic_get_new_crtc_state(state, crtc);
 	u8 update_planes = crtc_state->update_planes;
-	const struct intel_plane_state *plane_state;
+	const struct intel_plane_state __maybe_unused *plane_state;
 	struct intel_plane *plane;
 	int i;
 
@@ -988,7 +988,7 @@ static void intel_crtc_disable_flip_done(struct intel_atomic_state *state,
 	const struct intel_crtc_state *crtc_state =
 		intel_atomic_get_new_crtc_state(state, crtc);
 	u8 update_planes = crtc_state->update_planes;
-	const struct intel_plane_state *plane_state;
+	const struct intel_plane_state __maybe_unused *plane_state;
 	struct intel_plane *plane;
 	int i;
 
@@ -5617,7 +5617,7 @@ static int intel_crtc_add_bigjoiner_planes(struct intel_atomic_state *state,
 					   struct intel_crtc *crtc,
 					   struct intel_crtc *other)
 {
-	const struct intel_plane_state *plane_state;
+	const struct intel_plane_state __maybe_unused *plane_state;
 	struct intel_plane *plane;
 	u8 plane_ids = 0;
 	int i;
@@ -5660,7 +5660,7 @@ static int intel_atomic_check_planes(struct intel_atomic_state *state)
 {
 	struct drm_i915_private *dev_priv = to_i915(state->base.dev);
 	struct intel_crtc_state *old_crtc_state, *new_crtc_state;
-	struct intel_plane_state *plane_state;
+	struct intel_plane_state __maybe_unused *plane_state;
 	struct intel_plane *plane;
 	struct intel_crtc *crtc;
 	int i, ret;

drivers/gpu/drm/i915/display/intel_fbc.c

@@ -1254,7 +1254,7 @@ static bool __intel_fbc_pre_update(struct intel_atomic_state *state,
 bool intel_fbc_pre_update(struct intel_atomic_state *state,
 			  struct intel_crtc *crtc)
 {
-	const struct intel_plane_state *plane_state;
+	const struct intel_plane_state __maybe_unused *plane_state;
 	bool need_vblank_wait = false;
 	struct intel_plane *plane;
 	int i;
@@ -1309,7 +1309,7 @@ static void __intel_fbc_post_update(struct intel_fbc *fbc)
 void intel_fbc_post_update(struct intel_atomic_state *state,
 			   struct intel_crtc *crtc)
 {
-	const struct intel_plane_state *plane_state;
+	const struct intel_plane_state __maybe_unused *plane_state;
 	struct intel_plane *plane;
 	int i;
 
@@ -1408,7 +1408,7 @@ void intel_fbc_flush(struct drm_i915_private *i915,
 
 int intel_fbc_atomic_check(struct intel_atomic_state *state)
 {
-	struct intel_plane_state *plane_state;
+	struct intel_plane_state __maybe_unused *plane_state;
 	struct intel_plane *plane;
 	int i;