This does a bit of refactoring of the bsp-generation code to make it
generically reusable for generating non-bsp layers.
The first user remains the existing yocto-bsp tool; these changes
allow a second user, the new yocto-layer tool, to use the same code.
(From meta-yocto rev: 1527a0ee7bce08a527c9d80516531b17816dff17)
Signed-off-by: Tom Zanussi <tom.zanussi@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>