Revert unwanted buildroot change

In commit 166344752c98 ("bump kernel to 5.3.16 for Blackbird too") the
buildroot commit was changed accidentally.

Signed-off-by: Joel Stanley <joel@jms.id.au>
diff --git a/buildroot b/buildroot
index d93a0b4..d2eb9d6 160000
--- a/buildroot
+++ b/buildroot
@@ -1 +1 @@
-Subproject commit d93a0b402934309c632d4a825b7fe6183ce8c4c7
+Subproject commit d2eb9d62c1f1651c49369fe566c8f989134f9c09