staging: r8188eu: action category ht is not used

The r8188eu driver does not handle the ht action category. Remove the
empty handler function, the entry in OnAction_tbl and the define for the
category.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20220502200652.143665-2-martin@kaiser.cx


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