staging: wlan-ng: Remove unused struct wlan_ie_ibss_parms references

staging: wlan-ng: Remove unused struct wlan_ie_ibss_parms references

Pointer reference to struct wlan_ie_ibss_parms is added as a member
variable to 2 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/e53084cdd3ca3ffea6a32393f6f28c7b7650d1a4.1667308828.git.drv@mailo.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>