drm/ssd130x: Fix possible uninitialized usage of crtc_state variable

Avoid a possible uninitialized use of the crtc_state variable in function
ssd132x_primary_plane_atomic_check() and avoid the following Smatch warn:

    drivers/gpu/drm/solomon/ssd130x.c:921 ssd132x_primary_plane_atomic_check()
    error: uninitialized symbol 'crtc_state'.

Fixes: fdd591e ("drm/ssd130x: Add support for the SSD132x OLED controller family")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/dri-devel/7dd6ca45-8263-44fe-a318-2fd9d761425d@moroto.mountain/
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231020225338.1686974-1-javierm@redhat.com

drivers/gpu/drm/solomon/ssd130x.c

@@ -910,7 +910,7 @@ static int ssd132x_primary_plane_atomic_check(struct drm_plane *plane,
 	struct drm_plane_state *plane_state = drm_atomic_get_new_plane_state(state, plane);
 	struct ssd130x_plane_state *ssd130x_state = to_ssd130x_plane_state(plane_state);
 	struct drm_crtc *crtc = plane_state->crtc;
-	struct drm_crtc_state *crtc_state;
+	struct drm_crtc_state *crtc_state = NULL;
 	const struct drm_format_info *fi;
 	unsigned int pitch;
 	int ret;