netfilter: fixup the quota2, and enable.

netfilter: fixup the quota2, and enable.

The xt_quota2 came from
  http://sourceforge.net/projects/xtables-addons/develop

It needed tweaking for it to compile within the kernel tree.
Fixed kmalloc() and create_proc_entry() invocations within
 a non-interruptible context.
Removed useless copying of current quota back to the iptable's
struct matchinfo:
  - those are per CPU: they will change randomly based on which
    cpu gets to update the value.
  - they prevent matching a rule: e.g.
      -A chain -m quota2 --name q1 --quota 123
     can't be followed by
      -D chain -m quota2 --name q1 --quota 123
    as the 123 will be compared to the struct matchinfo's quota member.
Use the NETLINK NETLINK_NFLOG family to log a single message
when the quota limit is reached.
It uses the same packet type as ipt_ULOG, but
 - never copies skb data,
 - uses 112 as the event number (ULOG's +1)
It doesn't log if the module param "event_num" is 0.

Change-Id: I021d3b743db3b22158cc49acb5c94d905b501492
Signed-off-by: JP Abgrall <jpa@google.com>