1) Move ARC OTG USB (used in PP502x) driver code into it's own file, drivers/arcotg_udc.c. Hopefully in the future we will be able to adapt more of the Linux driver and add it to this file.
2) Rename mx31.h to arcotg_udc.h to reflect the file the code came from. It's also a more accurate name for the USB controller.
3) Get rid of one more inl()/outl() in usb-pp.c and use the relevant #define instead.
4) Add dr_controller_stop(). Not used yet.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@12340 a1c6a512-1295-4272-9138-f99709370657
