drm/vc4: Fix leak of HDMI EDID

We don't keep a pointer to it around anywhere, so it's our job to free
it.

Cc: Stefan Wahren <stefan.wahren@i2se.com>
Link: anholt#101
Fixes: c8b75bc ("drm/vc4: Add KMS support for Raspberry Pi.")
Signed-off-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20170808205605.4432-1-eric@anholt.net
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
(cherry picked from commit 5afe0e6)

drivers/gpu/drm/vc4/vc4_hdmi.c

@@ -243,6 +243,7 @@ static int vc4_hdmi_connector_get_modes(struct drm_connector *connector)
 	drm_mode_connector_update_edid_property(connector, edid);
 	ret = drm_add_edid_modes(connector, edid);
 	drm_edid_to_eld(connector, edid);
+	kfree(edid);
 
 	return ret;
 }