meta-google: Disable u-boot shell for Google prod builds

The DISTRO_FEATURE option for this is merged,
https://gerrit.openbmc-project.xyz/c/openbmc/openbmc/+/45523

Signed-off-by: Vivekanand Veeracholan <vveerach@google.com>
Change-Id: I70ba330f1f39aa785a31b63d1640a4c4b3c3eba8
diff --git a/meta-google/conf/distro/gbmc.conf b/meta-google/conf/distro/gbmc.conf
index 50fdc59..bbba7ef 100644
--- a/meta-google/conf/distro/gbmc.conf
+++ b/meta-google/conf/distro/gbmc.conf
@@ -17,6 +17,9 @@
 # Required to get entity-manager to build with FruDevice service
 DISTRO_FEATURES:append = " ipmi-fru"
 
+# Disable u-boot shell for prod builds
+DISTRO_FEATURES:append:prod = " disable-u-boot-shell"
+
 WATCHDOG_PKG ?= "watchdog"
 
 SANITY_TESTED_DISTROS:append = " Debian-rodete \n debian-rodete \n "