wil6210: Fix kernel oops in reset flow

wil_reset() removes vring's
At the same time NAPI may be active performing Rx/Tx completion.
If this happens, Rx/Tx polling functions going to access already removed vrings

Make sure NAPI is idle and won't be started prior to vring removal.
For this, track NAPI enabled state

Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/wil6210/wil6210.h

@@ -249,6 +249,7 @@ enum { /* for wil6210_priv.status */
 	wil_status_dontscan,
 	wil_status_reset_done,
 	wil_status_irqen, /* FIXME: interrupts enabled - for debug */
+	wil_status_napi_en, /* NAPI enabled protected by wil->mutex */
 };
 
 struct pci_dev;