meta-nicole: Enable field mode

Enables the field mode by default.
This marks the BMC as production version and activates some production
specific functionalities.
For example, this makes the software manager to discard unverified
firmware images.

Tested:
 - The output of `fw_printenv` contains `fieldmode=true`.
 - `busctl get-property xyz.openbmc_project.Software.BMC.Updater \
          /xyz/openbmc_project/software \
          xyz.openbmc_project.Control.FieldMode FieldModeEnabled`
   returns `true`

Change-Id: I66b6b49658bb5745ea4aa6ed35c3a6077a4c2027
Signed-off-by: Alexander Filippov <a.filippov@yadro.com>
diff --git a/meta-nicole/recipes-bsp/u-boot/u-boot-aspeed_%.bbappend b/meta-nicole/recipes-bsp/u-boot/u-boot-aspeed_%.bbappend
index f0ff09e..bf7802a 100644
--- a/meta-nicole/recipes-bsp/u-boot/u-boot-aspeed_%.bbappend
+++ b/meta-nicole/recipes-bsp/u-boot/u-boot-aspeed_%.bbappend
@@ -2,4 +2,5 @@
 
 SRC_URI_append = " \
     file://0001-Add-system-reset-status-support.patch \
+    file://0002-config-ast-common-set-fieldmode-to-true.patch \
     "