Move community board support files and recipes to meta-agl-devel

The list of boards is growing:

• cyclone5
• dra7xx-evm
• dragonboard-410c
• h3ulcb
• imx6qsabrelite
• intel-corei7-64
• joule
• m3ulcb (+nogfx)
• nitrogen6x
• porter
• qemux86 / qemux86-64
• raspberrypi2
• raspberrypi3
• wandboard

In the last AGL release (CC), only 3 boards are used as Reference Boards:

• porter
• intel-corei7-64
• qemux86-64

This is a proposal to make some cleanup in meta-agl (core layer) and move community boards support files into meta-agl-devel. This is a solution to isolate the non-maintained (or poorly-maintained) boards outside of main layers. Typically, the move to weston 1.11 (see SPEC-411) shows that changing a major component version for all BSPs at once is very difficult, as not all BSPs support the new version.

Moving community boards support in meta-agl-devel provides a clear separation between official builds and community builds:

• moving forward on reference design should be easier
• it will also allow the community to align on the reference design at its own pace

In details, this can be done in few steps:

• create meta-agl-devel/templates/machines
• create meta-agl-devel/meta-agl-bsp
  Then, for all community boards:
• move files from meta-agl/templates/machines to meta-agl-devel/templates/machines
• move directories and related files from meta-agl/meta-agl-bsp to meta-agl-devel/meta-agl-bsp
• adjust meta-agl-devel/templates/machines// to reflect the new paths