powerpc/512x: fix clk_get() return value

clk_get() should return an ERR_PTR value on error, not NULL.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

arch/powerpc/platforms/512x/clock.c

@@ -57,7 +57,7 @@ static struct clk *mpc5121_clk_get(struct device *dev, const char *id)
 	int id_match = 0;
 
 	if (dev == NULL || id == NULL)
-		return NULL;
+		return clk;
 
 	mutex_lock(&clocks_mutex);
 	list_for_each_entry(p, &clocks, node) {