staging: r8188eu: replace OnAction_tbl with switch-case

OnAction_tbl has only three entries. It's simpler to use a switch
statement instead of iterating over the table.

We can then remove the table itself and struct action_handler, which was
used only for the table entries.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20220502200652.143665-7-martin@kaiser.cx


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