By cleaning up the code the compiler does not emit the following warning
anymore:

    src/barebox-state.c:44:14: warning: ‘__state_uint8_get’ declared ‘static’ but never defined [-Wunused-function]
     static char *__state_uint8_get(struct state_variable *var);
                  ^~~~~~~~~~~~~~~~~

The function is not needed as its job is done by __state_uint32_get().

Signed-off-by: Ulrich Ölmann <u.oelmann@pengutronix.de>
Signed-off-by: Roland Hieber <rhi@pengutronix.de>