Fix build-from-scratch issue with u-boot

A recent change in the u-boot-asspeed.inc caused a regression
when building an OpenBMC image from scratch.

Resolves openbmc/openbmc#3073

Change-Id: I8e75c7bba1733d885dfa342667012888c44f5f1e
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
diff --git a/meta-phosphor/common/recipes-bsp/u-boot/u-boot-aspeed.inc b/meta-phosphor/common/recipes-bsp/u-boot/u-boot-aspeed.inc
index 56d1235..6ec91b4 100644
--- a/meta-phosphor/common/recipes-bsp/u-boot/u-boot-aspeed.inc
+++ b/meta-phosphor/common/recipes-bsp/u-boot/u-boot-aspeed.inc
@@ -8,7 +8,7 @@
     file://0004-config-ast-common-Add-conditional-factory-reset-comm.patch \
     "
 
-do_patch[depends] = "os-release:do_populate_sysroot"
+do_patch[depends] += "os-release:do_populate_sysroot"
 
 python do_patch_append_aspeed_df-obmc-ubi-fs () {
     version_id=do_get_versionID(d)