brcmfmac: fix leak of mypkt on error return path

Currently if the call to brcmf_sdiod_set_backplane_window fails then
error return path leaks mypkt. Fix this by returning by a new
error path labelled 'out' that calls brcmu_pkt_buf_free_skb to free
mypkt.  Also remove redundant check on err before calling
brcmf_sdiod_skbuff_write.

Addresses-Coverity: ("Resource Leak")
Fixes: a7c3aa15 ("brcmfmac: Remove brcmf_sdiod_addrprep()")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/broadcom/brcm80211/brcmfmac/bcmsdh.c

@@ -628,15 +628,13 @@ int brcmf_sdiod_send_buf(struct brcmf_sdio_dev *sdiodev, u8 *buf, uint nbytes)
 
 	err = brcmf_sdiod_set_backplane_window(sdiodev, addr);
 	if (err)
-		return err;
+		goto out;
 
 	addr &= SBSDIO_SB_OFT_ADDR_MASK;
 	addr |= SBSDIO_SB_ACCESS_2_4B_FLAG;
 
-	if (!err)
-		err = brcmf_sdiod_skbuff_write(sdiodev, sdiodev->func2, addr,
-					       mypkt);
-
+	err = brcmf_sdiod_skbuff_write(sdiodev, sdiodev->func2, addr, mypkt);
+out:
 	brcmu_pkt_buf_free_skb(mypkt);
 
 	return err;