include/linux/usb.h causes a lot of -Wshadow warnings - fix them.

  include/linux/usb.h:901: warning: declaration of 'complete' shadows a global declaration
  include/linux/completion.h:52: warning: shadowed declaration is here
  include/linux/usb.h:932: warning: declaration of 'complete' shadows a global declaration
  include/linux/completion.h:52: warning: shadowed declaration is here
  include/linux/usb.h:967: warning: declaration of 'complete' shadows a global declaration
  include/linux/completion.h:52: warning: shadowed declaration is here
Signed-off-by: NJesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>