libertas: fix uninitialized variable warning

Fixes:

drivers/net/wireless/libertas/rx.c: In function process_rxed_802_11_packet:
drivers/net/wireless/libertas/rx.c:354: error: radiotap_hdr.flags may be used uninitialized in this function

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/libertas/rx.c b/drivers/net/wireless/libertas/rx.c
index a115bfa..7a377f5 100644
--- a/drivers/net/wireless/libertas/rx.c
+++ b/drivers/net/wireless/libertas/rx.c
@@ -329,9 +329,8 @@
 	/* create the exported radio header */
 
 	/* radiotap header */
-	radiotap_hdr.hdr.it_version = 0;
-	/* XXX must check this value for pad */
-	radiotap_hdr.hdr.it_pad = 0;
+	memset(&radiotap_hdr, 0, sizeof(radiotap_hdr));
+	/* XXX must check radiotap_hdr.hdr.it_pad for pad */
 	radiotap_hdr.hdr.it_len = cpu_to_le16 (sizeof(struct rx_radiotap_hdr));
 	radiotap_hdr.hdr.it_present = cpu_to_le32 (RX_RADIOTAP_PRESENT);
 	radiotap_hdr.rate = convert_mv_rate_to_radiotap(prxpd->rx_rate);