Squashed commit of the following:

commit 2a3ab1652a2c95bcfc8be8380fc7cbdcb6472938
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Sat Aug 19 08:44:31 2017 -0600

    PF_IEEE802154: Finish some missing bind() logic.  Add configs/sim configuration for testing.

commit 59be4b846a6e3bfe82087a888e3fdac9c3c414e5
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 19:30:04 2017 -0600

    PF_IEEE802154:  More renaming to decouple 6LoPAN from radios in general.

commit 69fabb1aea76e54381bdc13de28a3f1441fb42f4
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 19:21:11 2017 -0600

    PF_IEEE802154: Missed a few renamings.

commit ff0af1bb25567720934cc1c2a721ccd92cc35f89
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 17:46:58 2017 -0600

    PF_IEEE802154:  A few bugfixes

commit 01c7c84afd00cf907d280d30cfaf0fb2cf90e02e
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 17:01:31 2017 -0600

    PF_IEEE802154:  A few bugfixes

commit dcef4056d1c1488c93151135f3b7106977faa903
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 16:31:05 2017 -0600

    PF_IEEE802154: Bring in framework for sendto/recvfrom.  Currently just a crude port of functions from net/pkt and do not provide the implemenation needed.

commit 68c5b7b6dd3ab7eb2d0c19890abb38e6561b140e
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 15:18:31 2017 -0600

    Trivial fix to typo in comment

commit fd0af534c089569ccdbd59f13b85453de0a653ad
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 15:07:20 2017 -0600

    PF_IEEE802154: Add device lookup logic; Rename some things that used to be used only by 6LoWPAN but now must be shared with PF_IEEE802154 and need more generic naming.

commit 4fc80a1659f1c699b050775cefc7f6b631b46114
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 13:49:54 2017 -0600

    PF_IEEE802154: Add driver poll logic.

commit d83f71992df8764faa93f9425f1a7602a758f730
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 13:28:59 2017 -0600

    PF_IEEE802154:  Add frame input function.

commit 77561b8c4d5d7be1f8d8eb62cf1a07229afe2048
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 12:46:29 2017 -0600

    PF_IEEE802154: Socket type should be SOCK_DGRAM.  Hook in socket interface.

commit c0f90350282e9905d7f26a1b30f04cc6d6794648
Merge: 8b518abfd0 169c55e5
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 09:36:32 2017 -0600

    Merge remote-tracking branch 'origin/master' into pf_ieee802154

commit 8b518abfd07d492f5148f2c5fdf65604de9822da
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 09:35:39 2017 -0600

    PF_IEEE802154: Add initialization and connection management logic.

commit 98b62620b3cb420041d8ad14204f9410a8aace8c
Author: Gregory Nutt <gnutt@nuttx.org>
Date:   Fri Aug 18 07:52:51 2017 -0600

    PF_IEEE802154: Add basic build support and socket interface framework.