regulator: core: fix possible NULL dereference

We were checking rdev->supply for NULL after dereferencing it. Lets
check for rdev->supply along with _regulator_is_enabled() and call
regulator_enable() only if rdev->supply is not NULL.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -1422,11 +1422,10 @@ static int regulator_resolve_supply(struct regulator_dev *rdev)
 		return ret;
 
 	/* Cascade always-on state to supply */
-	if (_regulator_is_enabled(rdev)) {
+	if (_regulator_is_enabled(rdev) && rdev->supply) {
 		ret = regulator_enable(rdev->supply);
 		if (ret < 0) {
-			if (rdev->supply)
-				_regulator_put(rdev->supply);
+			_regulator_put(rdev->supply);
 			return ret;
 		}
 	}