meta-aspeed: linux-aspeed: fix SRC_URI to append

Modifications to the SRC_URI should be append rather than a set
operation, so that they do not erase any changed to the SRC_URI that may
have happened prior to the include file.  Otherwise, it can ignore local
patches being applied for testing, which can make for irate developers.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I9bd95352fa30bd0e8dfd89404d2ac0dbb4d78a3a
diff --git a/meta-aspeed/recipes-kernel/linux/linux-aspeed.inc b/meta-aspeed/recipes-kernel/linux/linux-aspeed.inc
index 0f3d5ef..76d96ff 100644
--- a/meta-aspeed/recipes-kernel/linux/linux-aspeed.inc
+++ b/meta-aspeed/recipes-kernel/linux/linux-aspeed.inc
@@ -7,7 +7,7 @@
 KCONFIG_MODE="--alldefconfig"
 
 KSRC ?= "git://github.com/openbmc/linux;protocol=https;branch=${KBRANCH}"
-SRC_URI = "${KSRC}"
+SRC_URI += "${KSRC}"
 SRC_URI += " \
              file://defconfig \
              file://rsa_oem_fitimage_key.key;sha256sum=eeb4ff2ebbfbd97b6254fe6dbaeea41067e54c65176c233ec7b2ab2decf1ddcd \