CHROMIUM: WAR: ath10k: Clear need_gtk and need_ptk flags during stop AP

Currently, need_gtk and need_ptk flags are set per interface in
ieee80211_start_ap but not unset in ieee80211_stop_ap. This leads
to wrong flags set in peer assoc cmd sent to firmware when any STA or
mesh is started on the same interface.

Fix this issue by clearing the need_ptk and need_gtk bit during
ieee80211_stop_ap.

BUG=b:132147953
TEST=None

Change-Id: Icbe030ef57506d21cc8bf72ca2d72bb99f2c511b
Signed-off-by: Surabhi Vishnoi <svishnoi@codeaurora.org>
Signed-off-by: Vamsi Singamsetty <vamssi@codeaurora.org>