wl18xx: fix a bug in wl->num_rx_desc initialization

wl->num_rx_desc was mistakenly initialized with WL18XX_NUM_TX_DESCRIPTORS
but it should use WL18XX_NUM_RX_DESCRIPTORS instead.

This bug was passed unnoticed because currently both RX and TX descriptors
are initialized to the same value (32).

Signed-off-by: Yair Shapira <yair.shapira@ti.com>
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>

drivers/net/wireless/ti/wl18xx/main.c

@@ -1501,7 +1501,7 @@ static int wl18xx_setup(struct wl1271 *wl)
 
 	wl->rtable = wl18xx_rtable;
 	wl->num_tx_desc = WL18XX_NUM_TX_DESCRIPTORS;
-	wl->num_rx_desc = WL18XX_NUM_TX_DESCRIPTORS;
+	wl->num_rx_desc = WL18XX_NUM_RX_DESCRIPTORS;
 	wl->num_channels = 2;
 	wl->num_mac_addr = WL18XX_NUM_MAC_ADDRESSES;
 	wl->band_rate_to_idx = wl18xx_band_rate_to_idx;