musb_hdrc: remove broken Mentor OTG code

Remove most of the strange OTG-incompatible logic from Mentor, with
its CamelCasing and so forth.  It's better to trigger the transitions
explicitly with relevant operations, like suspend triggering HNP, than
trying to track a subset of the OTG triggers.

Plus some minor cleanups related to previous patches:  better fix
for the "use_dma=n" related compiler warning, pt_regs for omap2430.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>