drm/sun4i: Fix releasing node when enumerating enpoints

sun4i_drv_add_endpoints() has a memory leak since it uses of_node_put()
when remote is equal to NULL and does nothing when remote has a valid
pointer.

Invert the logic to fix memory leak.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180625120304.7543-7-jernej.skrabec@siol.net