drm/imx: Remove the bogus possible_clones setup

It's not at all clear what cloning options this driver supports.
So let's just clear possible_clones instead of setting it to some
bogus value.

v2: Adjust the FIXME (Daniel)

Cc: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200211162208.16224-5-ville.syrjala@linux.intel.com

drivers/gpu/drm/imx/imx-drm-core.c

@@ -139,8 +139,8 @@ int imx_drm_encoder_parse_of(struct drm_device *drm,
 
 	encoder->possible_crtcs = crtc_mask;
 
-	/* FIXME: this is the mask of outputs which can clone this output. */
-	encoder->possible_clones = ~0;
+	/* FIXME: cloning support not clear, disable it all for now */
+	encoder->possible_clones = 0;
 
 	return 0;
 }