regulator: core: Warn on missing struct device

The core really wants a struct device to be supplied for regulators and
there's no reason this should be impossible so provide one so complain
if we didn't get one.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@ti.com>

drivers/regulator/core.c

@@ -2941,6 +2941,7 @@ regulator_register(const struct regulator_desc *regulator_desc,
 		return ERR_PTR(-EINVAL);
 
 	dev = config->dev;
+	WARN_ON(!dev);
 
 	if (regulator_desc->name == NULL || regulator_desc->ops == NULL)
 		return ERR_PTR(-EINVAL);