ath10k: fix a warning during channel switch with multiple vaps

ath10k: fix a warning during channel switch with multiple vaps

Doing a channel switch via hostapd_cli seems to update
the new channel context for each VAP's appropriately as below
in 'ath10k_mac_update_vif_chan', hence we can safely suppress the
warning that shows up during this operation and dump the warning only
if no vaps are available for channel switch

hostapd_cli -i wlan0 chan_switch 5 5200
OK

ath10k_pci : mac chanctx switch n_vifs 3 mode 1
ath10k_pci : mac chanctx switch vdev_id 2 freq 5180->5200 width 0->0
ath10k_pci : mac chanctx switch vdev_id 1 freq 5180->5200 width 0->0
ath10k_pci : mac chanctx switch vdev_id 0 freq 5180->5200 width 0->0

Call Trace:

WARNING: backports-20161201-3.14.77-9ab3068/drivers/net/wireless/ath/ath10k/mac.c:7126
[<c022f2d4>] (warn_slowpath_null) from [<bf7f150c>]
(ath10k_reconfig_complete+0xe4/0x25c [ath10k_core])
[<bf7f150c>] (ath10k_reconfig_complete [ath10k_core])
[<bf7f35f0>] (ath10k_mac_vif_ap_csa_work+0x214/0x370 [ath10k_core])
[<bf7f38b8>] (ath10k_mac_op_change_chanctx+0x108/0x128 [ath10k_core])
[<bf782ac0>] (ieee80211_recalc_chanctx_min_def+0x30c/0x430 [mac80211])
[<bf7830a4>] (ieee80211_recalc_smps_chanctx+0x2ec/0x840 [mac80211])
[<bf7843e8>] (ieee80211_vif_use_reserved_context+0x7c/0xf8 [mac80211])
[<bf7843e8>] (ieee80211_vif_use_reserved_context [mac80211])
[<bf76e5d4>] (ieee80211_csa_finalize_work+0x5c/0x88 [mac80211])

Fixes: d7bf4b4aba05 ("ath10k: fix ar->rx_channel updating logic")
Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>