filter: fix buffer sizes in filter plug-ins

filter: fix buffer sizes in filter plug-ins

Three of the filter plug-ins define arrays to hold output key values.
The arrays are sized based on the values of enums.  For example:

  enum output_keys {
    KEY_MAC_TYPE,
    KEY_MAC_PROTOCOL,
    KEY_MAC_SADDR,
    START_KEY = KEY_MAC_SADDR,
    KEY_MAC_DADDR,
    KEY_MAC_ADDR,
    MAX_KEY = KEY_MAC_ADDR,
  };

  static char hwmac_str[MAX_KEY - START_KEY][HWADDR_LENGTH];

The arrays are indexed by subtracting `START_KEY` from the enum value of
the key currently being processed: `hwmac_str[okey - START_KEY]`.
However, this means that the last key (`KEY_MAC_ADDR` in this example)
will run off the end of the array.  Increase the size of the arrays.

In the case of `IP2BIN` and `IP2HBIN`, there is no overrun, but only
because they use the wrong upper bound when looping over the keys, and
thus don't assign a value to the last key.  Correct the bound.

Also some small white-space tweaks.

Link: https://bugzilla.netfilter.org/show_bug.cgi?id=890
Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>