Include 'pure' configuration

configname: CONFIG_USB_FUNCTIONFS_GENERIC

USB Gadget Drivers
└─>Include 'pure' configuration
In linux kernel since version 2.6.35 (release Date: 2010-08-01)  
Include a configuration with the Function Filesystem alone with
no Ethernet interface.

depends
CONFIG_USB_FUNCTIONFS |
| CONFIG_USB_GADGET or CONFIG_USB_SUPPORT

is depended by
CONFIG_USB_FUNCTIONFS