payloads/U-Boot: Move to v2021.10

Move to building the latest U-Boot.

Signed-off-by: Simon Glass <sjg@chromium.org>
Change-Id: I33fcfc3135e55d16b0dcd8135217bd5adcef2099
Reviewed-on: https://review.coreboot.org/c/coreboot/+/59606
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/payloads/external/U-Boot/Makefile b/payloads/external/U-Boot/Makefile
index 90777a5..daadb3e 100644
--- a/payloads/external/U-Boot/Makefile
+++ b/payloads/external/U-Boot/Makefile
@@ -1,7 +1,6 @@
 ## SPDX-License-Identifier: GPL-2.0-only
 
-# 2019-4 tag
-STABLE_COMMIT_ID=3c99166441bf3ea325af2da83cfe65430b49c066
+STABLE_COMMIT_ID=v2021.07
 
 TAG-$(CONFIG_UBOOT_MASTER)=origin/master
 TAG-$(CONFIG_UBOOT_STABLE)=$(STABLE_COMMIT_ID)