staging: wlan-ng: Remove unused struct wlan_ie_ssid references

staging: wlan-ng: Remove unused struct wlan_ie_ssid references

Pointer reference to struct wlan_ie_ssid is added as a member variable
to 5 different structures. However, these references are never used.
Remove such unused struct references. The cleanup also renders the
struct useless; so remove it as well.
Issue identified as part of coccicheck based code analysis.

Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
Suggested-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: Deepak R Varma <drv@mailo.com>
Link: https://lore.kernel.org/r/6e39ef59d01d65a1e179f6aecfbb0d68b81fa257.1667308828.git.drv@mailo.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>