staging: fieldbus core: remove unused strings

Remove two unused static const strings - a leftover from
a previous stage. Interestingly, neither gcc nor sparse
warned about their presence.

Signed-off-by: Sven Van Asbroeck <TheSven73@gmail.com>
Link: https://lore.kernel.org/r/20190918183552.28959-2-TheSven73@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>