usb: gadget: Fix issue in config_desc with OS descriptor handling

If a gadget provides "OS descriptors" from the userspace then composite
gadget driver designates only one configuration which has OS descriptor
support to be used always with the hosts. With this we are seeing
enumeration issues in multi-config compositions where device does not
allowing Host to identify preferred configuration to choose.

Hence change the logic in config_desc for handling OS descriptor
configuration.

Change-Id: I5daa7631f9f2d634ee6b4b377b8d66283b21a497
Signed-off-by: Chandana Kishori Chiluveru <cchiluve@codeaurora.org>