google-usb-dyamic: support setting host MAC from BMC

This adds a MacIdx field from EM that indexing the MAC list reversely,
and set it as the host MAC.

Tested: On a machine the host MAC address is correctly set.

Fusion-Link: https://fusion2.corp.google.com/10b38e56-a8f0-3b09-8e81-5f2a3654fc4
Google-Bug-Id: 392923910
Change-Id: I8eaba4b32a7fc280d2151b1120e458f8e160b874
Signed-off-by: Yuxiao Zhang <yuxiaozhang@google.com>
diff --git a/meta-gbmc-staging b/meta-gbmc-staging
index dd22b20..5d466ed 160000
--- a/meta-gbmc-staging
+++ b/meta-gbmc-staging
@@ -1 +1 @@
-Subproject commit dd22b20aa6eb549cfa1c4579ac9281dc28a78181
+Subproject commit 5d466ed2b31c88fae334f68cb9bedbdbf6b18255