regulator: If we fail when setting up a supply say which supply

Makes it a bit easier to identify if it's a problem with the supplies,
the usual error would be omitting the supply name entirely.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>
1 file changed