netfilter: conntrack: use consistent style when defining inline functions

The header contains some inline functions defined as:

  static inline f (...)
  {
  #ifdef CONFIG_NF_CONNTRACK_EVENTS
    ...
  #else
    ...
  #endif
  }

and a few others as:

  #ifdef CONFIG_NF_CONNTRACK_EVENTS
  static inline f (...)
  {
    ...
  }
  #else
  static inline f (...)
  {
    ...
  }
  #endif

Prefer the former style, which is more numerous.

Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>