Merge branch '6lowpan'

Alexander Aring says:

====================
6lowpan: header cleanup

this patch series fix a missing include of 6LoWPAN header and move it
into the include/net directory. Since we did some code sharing with
bluetooth 6LoWPAN the header turns into a generic header for 6LoWPAN.
Instead to use a relative path in bluetooth 6LoWPAN we can now use
include <net/6lowpan.h>.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>