update edk2 to edk2-stable201905 tag

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

diff --git a/edk2 b/edk2
index 89910a39dcfd788057caa5d88b7e76e112d187b5..20d2e5a125e34fc8501026613a71549b2a1a3e54 160000 (submodule)
--- a/edk2
+++ b/edk2
@@ -1 +1 @@
-Subproject commit 89910a39dcfd788057caa5d88b7e76e112d187b5
+Subproject commit 20d2e5a125e34fc8501026613a71549b2a1a3e54