meta-google: gbmc-bridge: Fix gw source check

The conversion to ip_to_bytes picked the wrong address bytes off by one.
This fixes it and verifies that a machine now updates the address.

Change-Id: Ifc7bbebc0cf500d51d01d693445aa2533122e9a1
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-gw-src.sh b/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-gw-src.sh
index f765b0d..cfe993f 100644
--- a/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-gw-src.sh
+++ b/meta-google/recipes-google/networking/gbmc-bridge/gbmc-br-gw-src.sh
@@ -56,7 +56,7 @@
       echo "gBMC Bridge Ensure RA Invalid IP: $ip" >&2
       return 1
     fi
-    if (( ip_bytes[9] != 0xfd || ip_bytes[10] != 0 )); then
+    if (( ip_bytes[8] != 0xfd || ip_bytes[9] != 0 )); then
       return 0
     fi
     if [ "$action" = 'add' -a "$ip" != "$gbmc_br_gw_src_ip" ]; then