libffi: Use a more standard layout for patch files

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

diff --git a/meta/recipes-gnome/libffi/0001-libffi-update-for-3.0.11.patch b/meta/recipes-gnome/libffi/libffi/0001-libffi-update-for-3.0.11.patch
similarity index 100%
rename from meta/recipes-gnome/libffi/0001-libffi-update-for-3.0.11.patch
rename to meta/recipes-gnome/libffi/libffi/0001-libffi-update-for-3.0.11.patch