usb: core: Add support to parse config summary capability descriptors

This descriptor describes the list of functions present in a given
configuration. There should be one such descriptor per configuration
supported by the device. The order in which these descriptors appear
in the BOS descriptor reflects the order of preference of configurations
as desired by the device for optimal functionality. Configuration Summary
descriptors are used by Host software to decide which Configuration to set
to obtain the desired functionality.

Change-Id: I7ec095ce19caa690c0d3dc0fdd3add5ad37a74f3
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>