ARM: omap1: move mach/usb.h to include/linux/soc

The register definitions in this header are used in at least four
different places, with little hope of completely cleaning that up.

Split up the file into a portion that becomes a linux-wide header
under include/linux/soc/ti/, and the parts that are actually only
needed by board files.

Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>