multilib: Remove recipe from multilib.conf that inherits allarch

multilib: Remove recipe from multilib.conf that inherits allarch

Recipes like update-rc.d and qemu-config inherit "allarch", thus we
shouldn't add multilib BBCLASSEXTEND for them in multilib.conf.

Besides, we need to add multilib packages as the RPROVIDER contents for
those recipes, in order to avoid the NoProvider error when parsing.

[YOCTO #1471]

Signed-off-by: Dongxiao Xu <dongxiao.xu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>