clk: ti: autoidle: add checks against NULL pointer reference

The clk pointer passed to omap2_clk_(deny|allow)_idle can be NULL, so
add checks for this.

Reported-by: Dan Murphy <[e-mail]>
Signed-off-by: Tero Kristo <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Stephen Boyd <[e-mail]>

drivers/clk/ti/autoidle.c

···
  */
 int omap2_clk_deny_idle(struct clk *clk)
 {
-	struct clk_hw *hw = __clk_get_hw(clk);
+	struct clk_hw *hw;
+
+	if (!clk)
+		return -EINVAL;
+
+	hw = __clk_get_hw(clk);
 
 	if (omap2_clk_is_hw_omap(hw)) {
 		struct clk_hw_omap *c = to_clk_hw_omap(hw);
···
  */
 int omap2_clk_allow_idle(struct clk *clk)
 {
-	struct clk_hw *hw = __clk_get_hw(clk);
+	struct clk_hw *hw;
+
+	if (!clk)
+		return -EINVAL;
+
+	hw = __clk_get_hw(clk);
 
 	if (omap2_clk_is_hw_omap(hw)) {
 		struct clk_hw_omap *c = to_clk_hw_omap(hw);