ath6kl: fix typos in comments

Various spelling mistakes in comments.
Detected with the help of Coccinelle.
Signed-off-by: NJulia Lawall <Julia.Lawall@inria.fr>
Signed-off-by: NKalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20220314115354.144023-4-Julia.Lawall@inria.fr

drivers/net/wireless/ath/ath6kl/htc_mbox.c

@@ -1538,7 +1538,7 @@ static int ath6kl_htc_rx_alloc(struct htc_target *target,
 					     queue, n_msg);
 
 		/*
-		 * This is due to unavailabilty of buffers to rx entire data.
+		 * This is due to unavailability of buffers to rx entire data.
 		 * Return no error so that free buffers from queue can be used
 		 * to receive partial data.
 		 */