update ZFS to include important fixes staged for 2.2.1

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

diff --git a/submodules/zfsonlinux b/submodules/zfsonlinux
index 88fd6e053b4cbfa197d04d4263eb176795b70977..e295f30e6acc962f76a71306a569f292994614c0 160000 (submodule)
--- a/submodules/zfsonlinux
+++ b/submodules/zfsonlinux
@@ -1 +1 @@
-Subproject commit 88fd6e053b4cbfa197d04d4263eb176795b70977
+Subproject commit e295f30e6acc962f76a71306a569f292994614c0