brcmfmac: use ndev->needed_headroom to reserve additional header space

When using nmap tool with FMAC, the nmap packets were be dropped by kernel
because the size was too short. The kernel message showed like
"nmap: packet size is too short (42 <= 50)". It is caused by the packet
length is shorter than ndev->hard_header_len. According to LL_RESERVED_SPACE()
and hard_header_len definition, we should use hard_header_len to reserve L2
header, like ethernet header(ETH_HLEN) in our case and use needed_headroom for
the additional headroom needed by hardware.

[ Patch from Broadcom ]

See: raspberrypi/linux#1357

Signed-off-by: Phil Elwell <[email protected]>

Author: Phil Elwell

drivers/net/wireless/brcm80211/brcmfmac/core.c

@@ -696,7 +696,7 @@ int brcmf_net_attach(struct brcmf_if *ifp, bool rtnl_locked)
 	/* set appropriate operations */
 	ndev->netdev_ops = &brcmf_netdev_ops_pri;
 
-	ndev->hard_header_len += drvr->hdrlen;
+	ndev->needed_headroom += drvr->hdrlen;
 	ndev->ethtool_ops = &brcmf_ethtool_ops;
 
 	drvr->rxsz = ndev->mtu + ndev->hard_header_len +