meta-google: set FLASH_UBOOT_ENV_OFFSET as FLASH_KERNEL_OFFSET

After https://gerrit.openbmc.org/c/openbmc/openbmc/+/61622, we need to
set the offset for uboot environment.

Change-Id: I573ba1139b90041a66ff7fe15635823545f0ba9f
Signed-off-by: Tom Tung <shes050117@gmail.com>
diff --git a/meta-google/classes/image_types_hoth.bbclass b/meta-google/classes/image_types_hoth.bbclass
index 912b722..ae65d61 100644
--- a/meta-google/classes/image_types_hoth.bbclass
+++ b/meta-google/classes/image_types_hoth.bbclass
@@ -3,12 +3,14 @@
 FLASH_IMAGE_DESC_OFFSET:hoth = "${@960 if FLASH_SIZE == '65536' else 7232}"
 FLASH_HOTH_UPDATE_OFFSET:hoth = "${@1024 if FLASH_SIZE == '65536' else 31744}"
 FLASH_HOTH_MAILBOX_OFFSET:hoth = "${@65472 if FLASH_SIZE == '65536' else 7168}"
-unset FLASH_UBOOT_ENV_OFFSET
 
 # 64 bit kernels are larger, so they require a different layout
 FLASH_IMAGE_DESC_OFFSET:hoth:aarch64 = "${@61312 if FLASH_SIZE == '65536' else 7232}"
 FLASH_HOTH_UPDATE_OFFSET:hoth:aarch64 = "${@61376 if FLASH_SIZE == '65536' else 31744}"
 
+# Leave a zero-size u-boot env partition.
+FLASH_UBOOT_ENV_OFFSET = ${FLASH_KERNEL_OFFSET}
+
 python do_generate_static:append() {
     _append_image(os.path.join(d.getVar('DEPLOY_DIR_IMAGE', True),
                                'image-hoth-update'),