meta-aspeed: prep for new override syntax

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I8135871ae0e3b360aff7d878f7cf04a2504f2dd0
diff --git a/meta-aspeed/recipes-bsp/u-boot/u-boot-aspeed_2016.07.bb b/meta-aspeed/recipes-bsp/u-boot/u-boot-aspeed_2016.07.bb
index 8cebe5a..395f5ab 100644
--- a/meta-aspeed/recipes-bsp/u-boot/u-boot-aspeed_2016.07.bb
+++ b/meta-aspeed/recipes-bsp/u-boot/u-boot-aspeed_2016.07.bb
@@ -6,4 +6,4 @@
 
 # FIXME this can/should be removed when we have rebased off our
 # 2016 snapshot onto a more modern (circa late 2018) u-boot tree.
-BUILD_CFLAGS_remove = "-isystem${STAGING_INCDIR_NATIVE}"
+BUILD_CFLAGS:remove = "-isystem${STAGING_INCDIR_NATIVE}"