usb: gadget: Add ep capabilities support

For a driver to claim an unused endpoint, the parameters are
matched against the EP descriptor fields. The new EP
capabilities model has type and direction fields which need to be
populated properly, otherwise no EP desc is matched. Convert
endpoint configuration to new capabilities model by setting the
EP type and direction for each endpoint.

Change-Id: Ibbffc79ef9d8d047674765d148f174066c550b19
Signed-off-by: Ajay Agarwal <ajaya@codeaurora.org>