layer.conf: remove link to removed angstrom-feed-configs
layer.conf: remove link to removed angstrom-feed-configs

Signed-off-by: Andreas Müller <d72a15aaaca3a7afa855175c72dc8d2e05931e32@gmail.com>

schnitzeltony/meta-angstrom,schnitzeltony/meta-angstrom,schnitzeltony/meta-angstrom