linux-gen: makefile: fix out of tree build
linux-gen: makefile: fix out of tree build

Generated files need $(top_builddir) instead of $(top_srcdir)

Fixes bug https://bugs.linaro.org/show_bug.cgi?id=3052

Signed-off-by: Petri Savolainen <d528fd253b9aaf78fa72edbcc6249e82047f6ce6@linaro.org>
Reviewed-by: Bill Fischofer <52f3c909d51cc5d355a68a403df6906b3c1a8f83@linaro.org>
Signed-off-by: Maxim Uvarov <db4d16e02ae2d7493db430203537da8b2e34f290@linaro.org>

dkrot/odp,dkrot/odp,dkrot/odp,dkrot/odp