networking: make skb_put & friends return void pointers

It seems like a historic accident that these return unsigned char *,
and in many places that means casts are required, more often than not.

Make these functions (skb_put, __skb_put and pskb_put) return void *
and remove all the casts across the tree, adding a (u8 *) cast only
where the unsigned char pointer was used directly, all done with the
following spatch:

    @@
    expression SKB, LEN;
    typedef u8;
    identifier fn = { skb_put, __skb_put };
    @@
    - *(fn(SKB, LEN))
    + *(u8 *)fn(SKB, LEN)

    @@
    expression E, SKB, LEN;
    identifier fn = { skb_put, __skb_put };
    type T;
    @@
    - E = ((T *)(fn(SKB, LEN)))
    + E = fn(SKB, LEN)

which actually doesn't cover pskb_put since there are only three
users overall.

A handful of stragglers were converted manually, notably a macro in
drivers/isdn/i4l/isdn_bsdcomp.c and, oddly enough, one of the many
instances in net/bluetooth/hci_sock.c. In the former file, I also
had to fix one whitespace problem spatch introduced.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/mac80211/tdls.c b/net/mac80211/tdls.c
index 8674067..709ef02 100644
--- a/net/mac80211/tdls.c
+++ b/net/mac80211/tdls.c
@@ -49,7 +49,7 @@ static void ieee80211_tdls_add_ext_capab(struct ieee80211_sub_if_data *sdata,
 			  !ifmgd->tdls_wider_bw_prohibited;
 	struct ieee80211_supported_band *sband = ieee80211_get_sband(sdata);
 	bool vht = sband && sband->vht_cap.vht_supported;
-	u8 *pos = (void *)skb_put(skb, 10);
+	u8 *pos = skb_put(skb, 10);
 
 	*pos++ = WLAN_EID_EXT_CAPABILITY;
 	*pos++ = 8; /* len */
@@ -168,7 +168,7 @@ static void ieee80211_tdls_add_oper_classes(struct ieee80211_sub_if_data *sdata,
 
 static void ieee80211_tdls_add_bss_coex_ie(struct sk_buff *skb)
 {
-	u8 *pos = (void *)skb_put(skb, 3);
+	u8 *pos = skb_put(skb, 3);
 
 	*pos++ = WLAN_EID_BSS_COEX_2040;
 	*pos++ = 1; /* len */
@@ -209,7 +209,7 @@ static void ieee80211_tdls_add_link_ie(struct ieee80211_sub_if_data *sdata,
 		rsp_addr = sdata->vif.addr;
 	}
 
-	lnkid = (void *)skb_put(skb, sizeof(struct ieee80211_tdls_lnkie));
+	lnkid = skb_put(skb, sizeof(struct ieee80211_tdls_lnkie));
 
 	lnkid->ie_type = WLAN_EID_LINK_ID;
 	lnkid->ie_len = sizeof(struct ieee80211_tdls_lnkie) - 2;
@@ -223,7 +223,7 @@ static void
 ieee80211_tdls_add_aid(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
 {
 	struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
-	u8 *pos = (void *)skb_put(skb, 4);
+	u8 *pos = skb_put(skb, 4);
 
 	*pos++ = WLAN_EID_AID;
 	*pos++ = 2; /* len */
@@ -745,7 +745,7 @@ ieee80211_prep_tdls_encap_data(struct wiphy *wiphy, struct net_device *dev,
 	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 	struct ieee80211_tdls_data *tf;
 
-	tf = (void *)skb_put(skb, offsetof(struct ieee80211_tdls_data, u));
+	tf = skb_put(skb, offsetof(struct ieee80211_tdls_data, u));
 
 	memcpy(tf->da, peer, ETH_ALEN);
 	memcpy(tf->sa, sdata->vif.addr, ETH_ALEN);