imx-drm: imx-drm-core: delete unneeded test before of_node_put

Of_node_put supports NULL as its argument, so the initial test is not
necessary.

Suggested by Uwe Kleine-König.

The semantic patch that fixes this problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
expression e;
@@

-if (e)
   of_node_put(e);
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

@@ -471,7 +471,6 @@ int imx_drm_encoder_parse_of(struct drm_device *drm,
 		crtc_mask |= mask;
 	}
 
-	if (ep)
 	of_node_put(ep);
 	if (i == 0)
 		return -ENOENT;