OPP: Return correct value in dev_pm_opp_get_level

Commit 073d3d2 ("OPP: Level zero is valid") modified the
documentation for this function to indicate that errors should return a
non-zero value to avoid colliding with the OPP level zero, however
forgot to actually update the return.

No in-tree kernel code depends on the error value being 0.

Fixes: 073d3d2 ("OPP: Level zero is valid")
Signed-off-by: Aleks Todorov <aleksbgbg@google.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Author: Aleksbgbg

drivers/opp/core.c

@@ -241,7 +241,7 @@ unsigned int dev_pm_opp_get_level(struct dev_pm_opp *opp)
 {
 	if (IS_ERR_OR_NULL(opp) || !opp->available) {
 		pr_err("%s: Invalid parameters\n", __func__);
-		return 0;
+		return U32_MAX;
 	}
 
 	return opp->level;