staging: r8188eu: legacy_dz is initialised but never used

legacy_dz in struct sta_xmit_priv is initialised but not used. It can be
removed.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20230130195303.138941-7-martin@kaiser.cx


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