staging: r8188eu: remove unused data frame subtypes

Remove unused defines for data frame subtypes.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20220327180944.712545-7-martin@kaiser.cx


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