swconfig: make it compatible with 3.7

swconfig does not compile with 3.7 because

struct netlink_notify->pid    has been renamed to
struct netlink_notify->portid

and

struct genl_info->snd_pid     has been renamed to
struct genl_info->snd_portid

Use the new names and add compatibility patches
to 3.3 and 3.6.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@34288 3c298f89-4303-0410-b956-a3cf2f4a3e73