usb: gadget: Allow larger configuration descriptors

The composite framework allows gadgets with more than one function. This
can lead to situations where the configuration descriptor is larger than
the maximum of 512 bytes currently allowed by the composite framework.
This patch proposes to double that limit to 1024.

Signed-off-by: Robert Lukassen <robert.lukassen@tomtom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>