Fix a regression introduced in "iwlwifi: mvm: fix ht protection flags"
where an AP/IBSS MAC context could have been updated even before the
context was added to the FW. This fix avoids the following warning:

WARNING: ... at .../drivers/net/wireless/iwlwifi/mvm/mac-ctxt.c:1132
    iwl_mvm_mac_ctxt_changed+0x75/0x90 [iwlmvm]()
Changing inactive MAC 0c:8b:fd:01:1a:30/3
Modules linked in: [...]
Call Trace:
[<c16041fd>] dump_stack+0x41/0x52
[<c1041074>] warn_slowpath_common+0x84/0xa0
[<f80d8f45>] ? iwl_mvm_mac_ctxt_changed+0x75/0x90 [iwlmvm]
[<f80d8f45>] ? iwl_mvm_mac_ctxt_changed+0x75/0x90 [iwlmvm]
[<c1041133>] warn_slowpath_fmt+0x33/0x40
[<f80d8f45>] iwl_mvm_mac_ctxt_changed+0x75/0x90 [iwlmvm]
[<f80d517a>] iwl_mvm_bss_info_changed+0x22a/0x4b0 [iwlmvm]
[<c160831d>] ? mutex_unlock+0xd/0x10
[<f80d4678>] ? iwl_mvm_configure_filter+0x58/0x70 [iwlmvm]
[<f80d4f50>] ? iwl_mvm_mac_tx+0xc0/0xc0 [iwlmvm]
[<f8132d83>] ieee80211_bss_info_change_notify+0xa3/0x1d0 [mac80211]
[<f8149247>] ? ieee80211_del_virtual_monitor+0x127/0x1f0 [mac80211]
[<f8149cac>] ieee80211_do_open+0x12c/0xeb0 [mac80211]
[<c106c6de>] ? __raw_notifier_call_chain+0x1e/0x30
[<c106c70f>] ? raw_notifier_call_chain+0x1f/0x30
[<f814aa8d>] ieee80211_open+0x5d/0x60 [mac80211]
[<c1500c7b>] __dev_open+0xab/0x140
[<c160b39a>] ? _raw_spin_unlock_bh+0x2a/0x30
[<c1500f41>] __dev_change_flags+0x81/0x160
[<c10ab6fc>] ? __lock_is_held+0x3c/0x60
[<c15010d1>] dev_change_flags+0x21/0x60
Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Reported-by: Johannes Berg <johannes.berg@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>