Gigabeat S: Fully enable access to hardware tone controls and 3-D effect feature...

Gigabeat S: Fully enable access to hardware tone controls and 3-D effect feature. Under the hood, it's designated a hardware equalizer since it is one. Implement code framework for hardware EQ in general. Menu aspect is well abstracted and so the UI and strings can be changed around if taste doesn't quite suit. So far the emphasis is distinction of the UI labelling from the software EQ so that it's clear the settings are for a different thing.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@26051 a1c6a512-1295-4272-9138-f99709370657