staging: wlan-ng: Remove unused struct wlan_ie_supp_rates references

Pointer reference to struct wlan_ie_supp_rates is added as a member
variable to 7 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/370feb1f300896af66fa1c443d3ad19dc8934be3.1667308828.git.drv@mailo.com


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