cargo: Update to the latest kvm-ioctls version

We need to rely on the latest kvm-ioctls version to benefit from the
recent addition of unregister_ioevent(), allowing us to detach a
previously registered eventfd to a PIO or MMIO guest address.

Because of this update, we had to modify the current constraint we had
on the vmm-sys-util crate, using ">= 0.1.1" instead of being strictly
tied to "0.2.0".

Once the dependency conflict resolved, this commit took care of fixing
build issues caused by recent modification of kvm-ioctls relying on
EventFd reference instead of RawFd.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

vhost_user_backend/Cargo.toml

@@ -14,7 +14,7 @@ epoll = "4.1.0"
 libc = "0.2.65"
 vm-memory = { git = "https://github.com/rust-vmm/vm-memory" } 
 vm-virtio = { path = "../vm-virtio" }
-vmm-sys-util = "0.2.0"
+vmm-sys-util = ">=0.1.1"
 
 [dependencies.vhost_rs]
 path = "../vhost_rs"