[PATCH v4 bluetooth] Fix lowpan_rcv

[Martin Townsend <mtownsend1973@gmail.com>]

This series aims to fix incorrect return values in lowpan_rcv
To achieve this it also refactors the receive path to
  1) free skb only from lowpan_rcv and not functions that it calls
  2) move skb delivery from IPHC

I have only compile tested the changes for bluetooth as I don't have any HW
available so would be grateful for any testing from the Bluetooth developers.
I have done some minimal testing for IEEE802.15.4

Signed-off-by: Martin Townsend <martin.townsend@xsilon.com>
---

v1 -> v2:
* combined first two patches into one.
* split out renaming of process_data into a new patch
* re-use err in lowpan_process_data and remove err_ret local variable.
* removed third patch as applies to linux-wpan

v2 -> v3: (Updated from Alexander Aring's Review) 
* re-use err hadn't been included in patch.
* fixed some 'goto drop' cases in lowpan_rcv that should be 'goto drop skb'
* handle error codes when returning from lowpan_frag_rcv.
* Refactored lowpan_give_skb_to_devices so it consumes or free's skb and then
  only returns NET_RX status codes.

v3 -> v4: (Updated from Jukka Rissanen and Alexander Aring's Reviews)
* lowpan_process_data and process_data return skb or ERR_PTR, no need for 
  skb_inout
* prefer consume_skb on non error conditions.
* removed spurious setting of ret in lowpan_rcv

Martin Townsend (1):
  6lowpan: fix incorrect return values in lowpan_rcv

 include/net/6lowpan.h         |  4 +--
 net/6lowpan/iphc.c            | 73 ++++++++++++++++++-------------------------
 net/bluetooth/6lowpan.c       | 26 +++++++++------
 net/ieee802154/6lowpan_rtnl.c | 44 +++++++++++++++-----------
 4 files changed, 75 insertions(+), 72 deletions(-)

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1.9.1