util: vircgroupv2: mark only requested controllers as available
util: vircgroupv2: mark only requested controllers as available

When detecting available controllers on host we can be limited by list
of controllers from qemu.conf file.

Signed-off-by: Pavel Hrdina <d4772d05997b8abf035041e3b4f4996380ea7e7a@redhat.com>
Reviewed-by: Peter Krempa <2cf5c04c61aa466e4a47bfedc747d17279c72ffc@redhat.com>

jfehlig/libvirt,crobinso/libvirt,nertpinx/libvirt,andreabolognani/libvirt,crobinso/libvirt,zippy2/libvirt,fabianfreyer/libvirt,eskultety/libvirt,libvirt/libvirt,jardasgit/libvirt,jardasgit/libvirt,eskultety/libvirt,libvirt/libvirt,libvirt/libvirt,jardasgit/libvirt,andreabolognani/libvirt,nertpinx/libvirt,crobinso/libvirt,fabianfreyer/libvirt,olafhering/libvirt,eskultety/libvirt,olafhering/libvirt,zippy2/libvirt,jfehlig/libvirt,jfehlig/libvirt,andreabolognani/libvirt,jardasgit/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,fabianfreyer/libvirt,jfehlig/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,zippy2/libvirt,andreabolognani/libvirt,jardasgit/libvirt,olafhering/libvirt,nertpinx/libvirt,crobinso/libvirt,libvirt/libvirt,eskultety/libvirt,nertpinx/libvirt,olafhering/libvirt,eskultety/libvirt,zippy2/libvirt