[source] imx6: fix build breakage introduced in 9e41c3f54e3c

[LEDE Commits]

nbd pushed a commit to source.git, branch master:
https://git.lede-project.org/?p=source.git;a=commitdiff;h=7e7a31e6820e26951398bb1b6b508d6fb4c4b6e6

commit 7e7a31e6820e26951398bb1b6b508d6fb4c4b6e6
Author: Felix Fietkau <nbd at nbd.name>
AuthorDate: Sat Jul 2 19:33:10 2016 +0200

    imx6: fix build breakage introduced in 9e41c3f54e3c
    
    Signed-off-by: Felix Fietkau <nbd at nbd.name>
---
 target/linux/imx6/image/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target/linux/imx6/image/Makefile b/target/linux/imx6/image/Makefile
index 25c7bdf..236cf7f 100644
--- a/target/linux/imx6/image/Makefile
+++ b/target/linux/imx6/image/Makefile
@@ -142,7 +142,7 @@ define Device/ventana
   IMAGE/nand_normal.ubi := ubi-boot-overlay normal 2048 124KiB 128KiB 8124
   IMAGE/nand_large.ubi := ubi-boot-overlay large 4096 248KiB 256KiB 8124
   IMAGE/bootfs.tar.gz := bootfs.tar.gz
-  IMAGE_NAME := $$(IMAGE_PREFIX)-$$(1)-$$(2)
+  IMAGE_NAME = $$(IMAGE_PREFIX)-$$(1)-$$(2)
 endef
 
 define Device/wandboard