update zfsonlinux submodule to 2.0.1

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

diff --git a/submodules/zfsonlinux b/submodules/zfsonlinux
index 4a743804aa0720507b6f5572142ad1b0965d90f5..8f4d852dcdae10db7800a7007f0ac249536c49f8 160000 (submodule)
--- a/submodules/zfsonlinux
+++ b/submodules/zfsonlinux
@@ -1 +1 @@
-Subproject commit 4a743804aa0720507b6f5572142ad1b0965d90f5
+Subproject commit 8f4d852dcdae10db7800a7007f0ac249536c49f8