w1: fixes and bundling replies

A program can bundle a sequence of commands in one netlink packet but the kernel was having to reply in many different packets, this adds a flag W1_CN_BUNDLE in the cn_msg.flags to allow the kernel to bundle the replies in to one message. This is opt in to avoid breaking programs that aren't expecting additional messages.

Netlink connector now has a new call cn_netlink_send_multi, which allow sending multiple cn_msg structures in a nlmsghdr structure.

I tested with my client program that will bundle up 14 temperature sensor conversions, then after a delay, bundle up another set of commands to read all 14 with the bundle bit set. I also tested with a two year old version of the software that sends requests two one slave at a time (bundling only the write/read to get the data out), and doesn't have code to read the bundling the this patch adds. Both operate correctly running at the same time.

 Documentation/connector/connector.txt |   15 +-
 Documentation/w1/w1.generic           |    2 +-
 Documentation/w1/w1.netlink           |   13 +-
 drivers/connector/connector.c         |   17 +-
 drivers/w1/w1.h                       |    8 -
 drivers/w1/w1_netlink.c               |  673 ++++++++++++++++++++-------------
 drivers/w1/w1_netlink.h               |   36 ++
 include/linux/connector.h             |    1 +
 8 files changed, 489 insertions(+), 276 deletions(-)

[PATCH 1/3] w1: fix netlink refcnt leak on error path [PATCH 2/3] connector: allow multiple messages to be sent in one [PATCH 3/3] w1: optional bundling of netlink kernel replies