staging: rtl8192e: Remove dead code: r8192_priv members

Remove unused members of rtl8192_priv structure.
Some of them are never used, other are just initialized and
never accessed.

Signed-off-by: Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>