ath6kl: increase usb rx buffer size to 4096

With the previous value (1700), some urb are dropped
with a babble error (urb status equal -EOVERFLOW).

These error seems to only happen when urb length is a
multiple of packet size (512).
Signed-off-by: Julien Massot <jmassot@aldebaran-robotics.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

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

@@ -24,7 +24,7 @@
 /* constants */
 #define TX_URB_COUNT            32
 #define RX_URB_COUNT            32
-#define ATH6KL_USB_RX_BUFFER_SIZE  1700
+#define ATH6KL_USB_RX_BUFFER_SIZE  4096
 
 /* tx/rx pipes for usb */
 enum ATH6KL_USB_PIPE_ID {