imx8mm_venice: switch to use binman to pack images

Use binman to pack images.

Note that imx8mm_venice supports several boards via multiple DTB's thus
in the fit node we must use:
- fit,fdt-list = "of-list"
- fdt-SEQ
- config-SEQ

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Reviewed-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
diff --git a/board/gateworks/venice/Kconfig b/board/gateworks/venice/Kconfig
index 639bf35..687b94f 100644
--- a/board/gateworks/venice/Kconfig
+++ b/board/gateworks/venice/Kconfig
@@ -10,6 +10,5 @@
 	default "imx8mm_venice"
 
 config IMX_CONFIG
-	default "arch/arm/mach-imx/imx8m/imximage-8mm-lpddr4.cfg"
-
+	default "board/gateworks/venice/imximage-8mm-lpddr4.cfg"
 endif