Drop all custom sourcedir handling as the source is now a standard
git checkout.
(From OE-Core rev: 13965426b79e8c32f800a4317454321cfd2d06d1)
Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>