Allocate and initialize usb otg descriptor according to gadget otg
capabilities, add it for each usb configurations. If otg capability
is not defined, keep its original otg descriptor unchanged.
Reviewed-by: Roger Quadros <rogerq@ti.com> Signed-off-by: Li Jun <jun.li@freescale.com> Signed-off-by: Felipe Balbi <balbi@ti.com>