usb: f_mass_storage: set removable flag in do_inquiry based on LUN
Without this flag, tools like Alex Page's USB Image Tool
won't see drives exposed over USB Gadget as removable,
and won't allow access to them.
http://www.alexpage.de/usb-image-tool/
The code was pulled from the main-line kernel:
drivers/usb/gadget/function/f_mass_storage.c
Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>