staging: wlan-ng: Remove unused structure definitions

Remove structure definitions that are never used in the code.

Signed-off-by: Deepak R Varma <drv@mailo.com>
Link: https://lore.kernel.org/r/74a79ea400ec26624e445692f3353424fb6fc29e.1667308828.git.drv@mailo.com


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