iwlwifi: do not send lq cmd when station add fails

iwlwifi: do not send lq cmd when station add fails

When adding a station fails in
iwl_restore_stations, the driver treats it
like a successful station add and sends a
link quality command, when it it shouldn't.

This patch fixes one of the potential
sources for kernel warnings like this one:

WARNING: at drivers/net/wireless/iwlwifi/iwl-agn-sta.c:905 iwl_send_lq_cmd+0x130/0x217 [iwlwifi]()
Hardware name: 3323A2G
Modules linked in: ...
Pid: 17359, comm: kworker/u:2 Tainted: G           O 3.3.0-wl+ #1
Call Trace:
 [<ffffffff81039620>] warn_slowpath_common+0x7e/0x96
 [<ffffffff8103964d>] warn_slowpath_null+0x15/0x17
 [<ffffffffa02a9f0b>] iwl_send_lq_cmd+0x130/0x217 [iwlwifi]
 [<ffffffffa02aa1fb>] iwl_restore_stations+0x209/0x289 [iwlwifi]
 [<ffffffffa02b07c2>] iwlagn_commit_rxon+0x602/0x7bd [iwlwifi]
 [<ffffffffa02b111f>] iwlagn_bss_info_changed+0x247/0x31a [iwlwifi]
 [<ffffffffa0861437>] ieee80211_bss_info_change_notify+0x1a5/0x1ba [mac80211]
 [<ffffffffa088afad>] ieee80211_destroy_auth_data+0x4b/0x70 [mac80211]
 [<ffffffffa088df26>] ieee80211_sta_work+0xb5/0x954 [mac80211]

Signed-off-by: Meenakshi Venkataraman <meenakshi.venkataraman@intel.com>
Reviewed-by: Wey-Yi W Guy <wey-yi.w.guy@intel.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>