Add files related to ext2 HTree implementation

These should've been added along with r252890

Reported by:	gonzo
PointyHat:	pfg
MFC after:	1 week
Fix some typos.

MFC after:	1 week
- Add initial host mode support for Mentor Graphics USB OTG controller
- Sync musb_otg_atmelarm with new core logic API
- Add USBSS driver for AM335x SoC. Driver is a wrapper around Mentors Graphic
   USB OTG core.
- Add musb node to shared dtsi and proper pin configuratin for every
    AM553x-based device
- Add USFS driver as an example of device mode for AM335x-based devices