regulator: workaround self-referent regulators

Workaround regulators whose supply name happens to be the same as its
own name. This fixes boards that used to work before the early supply
resolving was removed. The error message is left in place so that
offending drivers can be detected.

Fixes: aea6cb9 ("regulator: resolve supply after creating regulator")
Cc: stable@vger.kernel.org
Reported-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Tested-by: Ahmad Fatoum <a.fatoum@pengutronix.de> # stpmic1
Link: https://lore.kernel.org/r/d703acde2a93100c3c7a81059d716c50ad1b1f52.1605226675.git.mirq-linux@rere.qmqm.pl
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -1844,7 +1844,10 @@ static int regulator_resolve_supply(struct regulator_dev *rdev)
 	if (r == rdev) {
 		dev_err(dev, "Supply for %s (%s) resolved to itself\n",
 			rdev->desc->name, rdev->supply_name);
-		return -EINVAL;
+		if (!have_full_constraints())
+			return -EINVAL;
+		r = dummy_regulator_rdev;
+		get_device(&r->dev);
 	}
 
 	/*