6lowpan: use stack buffer instead of heap

head buffer is only temporary available in lowpan_header_create.
So it's not necessary to put it on the heap.

Also fixed a comment codestyle issue.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 file changed