Update buildroot

Updated buildroot to 4b6ccffcfb84938d2f0813d7c98907d75b49b842 (current
master as of 2023-02-01)

Buildroot added a new package docopt-cpp which was in our custom added
packages. I have removed our package and we are using the one provided
by buildroot wich is (currently) fixed to version 0.6.3 while our was
building current docopt-cpp's master.

Change-Id: I5c0e4e04113a6c138100edb6bafd8722dacbcd4f
diff --git a/submodules/buildroot b/submodules/buildroot
index d7f2b9d..6610e4d 160000
--- a/submodules/buildroot
+++ b/submodules/buildroot
@@ -1 +1 @@
-Subproject commit d7f2b9ddf4641dab13243925ff2bea33ee0ea326
+Subproject commit 6610e4df3ca84d2ecee393e7025e5657801e08cc