qemu: migration: Assume support for QEMU_CAPS_BLOCKDEV_DEL
qemu: migration: Assume support for QEMU_CAPS_BLOCKDEV_DEL

The migration code was using few blockdev bits before blockdev was
fully integrated to allow TLS with NBD.

Since we now always use blockdev we can remove the check.

Signed-off-by: Peter Krempa <2cf5c04c61aa466e4a47bfedc747d17279c72ffc@redhat.com>
Reviewed-by: Pavel Hrdina <d4772d05997b8abf035041e3b4f4996380ea7e7a@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>

zippy2/libvirt,jfehlig/libvirt,olafhering/libvirt,libvirt/libvirt,zippy2/libvirt,libvirt/libvirt,olafhering/libvirt,olafhering/libvirt,jfehlig/libvirt,olafhering/libvirt,zippy2/libvirt,jfehlig/libvirt,jfehlig/libvirt,libvirt/libvirt,zippy2/libvirt,libvirt/libvirt