USB: TWL6025 allow different regulator name

The twl6025 uses a different regulator for USB than the 6030 so select
the correct regulator name depending on the subclass of device.

Since V1

Use features passed via platform data instead of global variable.

Signed-off-by: Graeme Gregory <gg@slimlogic.co.uk>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>