[NETLINK] genetlink: Fix bugs spotted by Andrew Morton.

- panic() doesn't return.

- Don't forget to unlock on genl_register_family() error path

- genl_rcv_msg() is called via pointer so there's no point in declaring it
  `inline'.

Notes:

genl_ctrl_event() ignores the genlmsg_multicast() return value.

lots of things ignore the genl_ctrl_event() return value.

Signed-off-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>