ucm: modifiers names must be compound parse

ucm: modifiers names must be compound parse

Modifier names must end in a .index to ensure we can support
same named modifiers. However the modifier index will be for internal
use only and the client will not use the index when setting modifier.

The modifier selection for same name modifiers will be based upon supported
device.

Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>