cfg80211: Use const more consistently in for_each_element macros

cfg80211: Use const more consistently in for_each_element macros

commit 7388afe09143210f555bdd6c75035e9acc1fab96 upstream.

Enforce the first argument to be a correct type of a pointer to struct
element and avoid unnecessary typecasts from const to non-const pointers
(the change in validate_ie_attr() is needed to make this part work). In
addition, avoid signed/unsigned comparison within for_each_element() and
mark struct element packed just in case.

Mot-CRs-fixed: (CR)
CVE-Fixed: CVE-2019-16746
Bug: 145728612

Signed-off-by: Jouni Malinen <j@w1.fi>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jignesh Patel <jignesh@motorola.com>
Change-Id: If727423ab9539110c78487a2e38f118060122e06
Reviewed-on: https://gerrit.mot.com/1681824
SLTApproved: Slta Waiver
SME-Granted: SME Approvals Granted
Tested-by: Jira Key
Reviewed-by: Xiangpo Zhao <zhaoxp3@motorola.com>
Submit-Approved: Jira Key
(cherry picked from commit 6f4e34bffb1d256cd6899814705859733de1c621)