regulator: dt: regulator-name is required property

These two drivers fail to probe if no name is provided. For details see:
https://www.spinics.net/lists/kernel/msg2457515.html



Signed-off-by: Harald Geyer <harald@ccbib.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>