Bump buildroot to 2020.08.2

Release notes: https://git.busybox.net/buildroot/tree/CHANGES?h=2020.08.2

Additional patches being carried:
 - a84aaae package/dropbear: Add separate configuration option for dropbear server
 - 050d2a5 Separate target-building make targets from image-building make targets

Additionally, glibc 2.31 from buildroot 2020.08 is adding around 10MB more storage
use on the rootfs, which in practice means around 1MB larger squashfs image. Bump
PNOR layout package version to address that.

Signed-off-by: Klaus Heinrich Kiwi <klaus@linux.vnet.ibm.com>
diff --git a/.gitmodules b/.gitmodules
index 085527d..499afdf 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,4 +1,4 @@
 [submodule "buildroot"]
 	path = buildroot
-	branch = 2019.05-op-build
+	branch = 2020.08.2-op-build
 	url = https://github.com/open-power/buildroot
diff --git a/buildroot b/buildroot
index 4a064c9..a84aaae 160000
--- a/buildroot
+++ b/buildroot
@@ -1 +1 @@
-Subproject commit 4a064c9005c800a115a81cc8be0627a35a5954d6
+Subproject commit a84aaaeacbd1a69053cde2e50f26250e9328de1e