drm/vc4: kms: Remove useless define

NUM_OUTPUTS isn't used anymore, let's remove it.
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Tested-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
Reviewed-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20201105135656.383350-3-maxime@cerno.tech

drivers/gpu/drm/vc4/vc4_kms.c

@@ -660,7 +660,6 @@ static int vc4_load_tracker_obj_init(struct vc4_dev *vc4)
 	return drmm_add_action_or_reset(&vc4->base, vc4_load_tracker_obj_fini, NULL);
 }
 
-#define NUM_OUTPUTS  6
 #define NUM_CHANNELS 3
 
 static int