regulator: core: Use IS_ERR_OR_NULL()

Use IS_ERR_OR_NULL() rather than open coding it.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 999a94b..5d61eb8 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1588,7 +1588,7 @@
 {
 	struct regulator_dev *rdev;
 
-	if (regulator == NULL || IS_ERR(regulator))
+	if (IS_ERR_OR_NULL(regulator))
 		return;
 
 	lockdep_assert_held_once(&regulator_list_mutex);