ath6kl: Fix bug in computing AMSU subframe padding

This fixes AMSDU rx, otherwise it fails with the following warnings.

"802.3 AMSDU frame bound check failed"

Signed-off-by: Vasanthakumar Thiagarajan <vthiagar@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
diff --git a/drivers/net/wireless/ath/ath6kl/txrx.c b/drivers/net/wireless/ath/ath6kl/txrx.c
index 5d3d4b6..44bf2271b 100644
--- a/drivers/net/wireless/ath/ath6kl/txrx.c
+++ b/drivers/net/wireless/ath/ath6kl/txrx.c
@@ -812,7 +812,7 @@
 		/* Add the length of A-MSDU subframe padding bytes -
 		 * Round to nearest word.
 		 */
-		frame_8023_len = ALIGN(frame_8023_len + 3, 3);
+		frame_8023_len = ALIGN(frame_8023_len, 4);
 
 		framep += frame_8023_len;
 		amsdu_len -= frame_8023_len;