PM / clk: Fix clock error check in __pm_clk_add()

commit 3fc3a0be upstream.

In the final iteration of commit 245bd6f6 ("PM / clock_ops: Add
pm_clk_add_clk()"), a refcount increment was added by Grygorii Strashko.
However, the accompanying IS_ERR() check operates on the wrong clock
pointer, which is always zero at this point, i.e. not an error.
This may lead to a NULL pointer dereference later, when __clk_get()
tries to dereference an error pointer.

Check the passed clock pointer instead to fix this.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Fixes: 245bd6f6 ("PM / clock_ops: Add pm_clk_add_clk()")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/power/clock_ops.c

@@ -93,7 +93,7 @@ static int __pm_clk_add(struct device *dev, const char *con_id,
 			return -ENOMEM;
 		}
 	} else {
-		if (IS_ERR(ce->clk) || !__clk_get(clk)) {
+		if (IS_ERR(clk) || !__clk_get(clk)) {
 			kfree(ce);
 			return -ENOENT;
 		}