Update buildroot

buildroot is now rebased to master, branch
cesnet/2021-12-03-rebase-to-master.

Change-Id: I9fccf4dff32833da9b95e997c351a1d01a109207
diff --git a/submodules/buildroot b/submodules/buildroot
index eef374b..4362720 160000
--- a/submodules/buildroot
+++ b/submodules/buildroot
@@ -1 +1 @@
-Subproject commit eef374bc84848cac16129c4c305dcf050203618e
+Subproject commit 4362720dd0e004a9b387c7308daa39c0a9d3635e