staging: r8188eu: remove action_public_str()

Function action_public_str() is not used, remove it.

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20210922200420.9693-31-straube.linux@gmail.com


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