clk: imx: scu: use _safe list iterator to avoid a use after free

This loop is freeing "clk" so it needs to use list_for_each_entry_safe().
Otherwise it dereferences a freed variable to get the next item on the
loop.

Fixes: 77d8f30 ("clk: imx: scu: add two cells binding support")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Abel Vesa <abel.vesa@linaro.org>
Link: https://lore.kernel.org/r/0793fbd1-d2b5-4ec2-9403-3c39343a3e2d@kili.mountain
Signed-off-by: Abel Vesa <abel.vesa@linaro.org>

Author: Dan Carpenter

drivers/clk/imx/clk-scu.c

@@ -707,11 +707,11 @@ struct clk_hw *imx_clk_scu_alloc_dev(const char *name,
 
 void imx_clk_scu_unregister(void)
 {
-	struct imx_scu_clk_node *clk;
+	struct imx_scu_clk_node *clk, *n;
 	int i;
 
 	for (i = 0; i < IMX_SC_R_LAST; i++) {
-		list_for_each_entry(clk, &imx_scu_clks[i], node) {
+		list_for_each_entry_safe(clk, n, &imx_scu_clks[i], node) {
 			clk_hw_unregister(clk->hw);
 			kfree(clk);
 		}