linux-yocto: locate and use out of tree features specified on the SRC_URI

linux-yocto: locate and use out of tree features specified on the SRC_URI

In a similar manner to calling the patch.bbclass to locate patches that
were listed on the SRC_URI, it is also useful to query about 'other' items
that are on the SRC_URI. In the case of linux-yocto, it allows us to
know about kernel features that were specific on the URI and then apply
them to the current tree.

(From OE-Core rev: 3e2ce87566124db8c78472f9a4f00ab26410f213)

Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>