staging: r8188eu: fix memleak in rtw_wx_set_enc_ext

commit 26f44837 upstream.

Free the param struct if the caller sets an unsupported algorithm
and we return an error.

Fixes: 2b42bd58

 ("staging: r8188eu: introduce new os_dep dir for RTL8188eu driver")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20211019202356.12572-1-martin@kaiser.cx
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>