[NETFILTER]: add some consts, remove some casts

Make a number of variables const and/or remove unneeded casts.

Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/netfilter/xt_MARK.c b/net/netfilter/xt_MARK.c
index bd9cdf2..6b7369f 100644
--- a/net/netfilter/xt_MARK.c
+++ b/net/netfilter/xt_MARK.c
@@ -72,7 +72,7 @@
 	      void *targinfo,
 	      unsigned int hook_mask)
 {
-	struct xt_mark_target_info *markinfo = targinfo;
+	const struct xt_mark_target_info *markinfo = targinfo;
 
 	if (markinfo->mark > 0xffffffff) {
 		printk(KERN_WARNING "MARK: Only supports 32bit wide mark\n");
@@ -88,7 +88,7 @@
 	      void *targinfo,
 	      unsigned int hook_mask)
 {
-	struct xt_mark_target_info_v1 *markinfo = targinfo;
+	const struct xt_mark_target_info_v1 *markinfo = targinfo;
 
 	if (markinfo->mode != XT_MARK_SET
 	    && markinfo->mode != XT_MARK_AND
@@ -114,7 +114,7 @@
 
 static void compat_from_user_v1(void *dst, void *src)
 {
-	struct compat_xt_mark_target_info_v1 *cm = src;
+	const struct compat_xt_mark_target_info_v1 *cm = src;
 	struct xt_mark_target_info_v1 m = {
 		.mark	= cm->mark,
 		.mode	= cm->mode,
@@ -124,7 +124,7 @@
 
 static int compat_to_user_v1(void __user *dst, void *src)
 {
-	struct xt_mark_target_info_v1 *m = src;
+	const struct xt_mark_target_info_v1 *m = src;
 	struct compat_xt_mark_target_info_v1 cm = {
 		.mark	= m->mark,
 		.mode	= m->mode,