3rdparty/chromeec: Update submodule to latest

From: 388a7fa8 (Wed, 10 Feb 2016)
CR50: remove incorrect output length check in RSA decrypt

To: 83b6d697 (Mon, 1 Aug 2016)
g: increase usb console TX buffer size to 4K

676 commits

Change-Id: Ic80de8b6fd6d9eba2a092b1a3493931241a2e48b
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/16021
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
diff --git a/3rdparty/chromeec b/3rdparty/chromeec
index 388a7fa..83b6d69 160000
--- a/3rdparty/chromeec
+++ b/3rdparty/chromeec
@@ -1 +1 @@
-Subproject commit 388a7fa8cff831dcb5f25a3ea4bd67de898d865a
+Subproject commit 83b6d69732f782e2b295153f959ec36d4a56c024