meta-aspeed: add CONFIG_USE_BOOTCOMMAND snippet

Add a config snippet that sets CONFIG_BOOTCOMMAND to the correct address
on 128MiB flashes.

This requires a refresh of the u-boot sdk patch we've been carrying such
that CONFIG_BOOTCOMMAND is set conditionally if not set previously.

Change-Id: I44adc4236991b718316ab52f0023d20ca5fb5f91
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/recipes-bsp/u-boot/u-boot-common-aspeed-sdk_2019.04.inc b/recipes-bsp/u-boot/u-boot-common-aspeed-sdk_2019.04.inc
index 83341e4..31dc5f2 100644
--- a/recipes-bsp/u-boot/u-boot-common-aspeed-sdk_2019.04.inc
+++ b/recipes-bsp/u-boot/u-boot-common-aspeed-sdk_2019.04.inc
@@ -14,6 +14,11 @@
 SRC_URI = "git://github.com/AspeedTech-BMC/u-boot;branch=${UBRANCH};protocol=https"
 SRC_URI += "file://0001-arm-evb-ast2600-put-environment-back-at-512KiB.patch"
 
+# There are different BOOTCOMMANDS for differently sized raw flash modules.
+ASPEED_IMAGE_SIZE_KB ?= "32768"
+MACHINEOVERRIDES .= ":flash-${ASPEED_IMAGE_SIZE_KB}"
+SRC_URI_append_flash-131072 = " file://bootcmd.cfg"
+
 S = "${WORKDIR}/git"
 
 PV = "v2019.04+git${SRCPV}"