modprobe: ignore builtin module on recursive removing

modprobe: ignore builtin module on recursive removing

If there are built-in dependencies and any of them is built-in in
the kernel, modprobe -r fails with

modprobe: FATAL: Module module_name is builtin.

It makes sense to ignore such dependencies for the case when
removing is called for non-top level module.

Example: cifs module, it declares bunch of softdeps and the first
one fails on some kernel configs:

modprobe: FATAL: Module gcm is builtin.

Signed-off-by: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>