[source] at91: fix legacy build

[LEDE Commits]

hauke pushed a commit to source.git, branch master:
https://git.lede-project.org/61048c901189d3d24ffc35e2e0ab2355f6ec0dbc

commit 61048c901189d3d24ffc35e2e0ab2355f6ec0dbc
Author: Hauke Mehrtens <hauke at hauke-m.de>
AuthorDate: Mon Oct 16 21:36:17 2017 +0200

    at91: fix legacy build
    
    The build system took the DTB_SIZE definition from Default and not from
    production-dtb under some conditions. Move the size definitions to
    Default now as it is only used in production-dtb anyway.
    
    Thanks Mathias Kresin for helping me with this.
    
    Fixes: c2f052acaeb ("at91: convert boards to generic build target")
    Signed-off-by: Hauke Mehrtens <hauke at hauke-m.de>
---
 target/linux/at91/image/Makefile | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/target/linux/at91/image/Makefile b/target/linux/at91/image/Makefile
index fedefe4..1260707 100644
--- a/target/linux/at91/image/Makefile
+++ b/target/linux/at91/image/Makefile
@@ -24,7 +24,7 @@ define Device/Default
   KERNEL_NAME := zImage
   KERNEL_SIZE := 4096k
   KERNEL := kernel-bin | append-dtb | lzma | uImage lzma
-  DTB_SIZE :=
+  DTB_SIZE := 128k
 endef
 
 define Device/dtb
@@ -66,7 +66,6 @@ endef
 define Device/production-dtb
   $(Device/production)
   $(Device/dtb)
-  DTB_SIZE := 128k
   IMAGE/factory.bin := append-dtb | pad-to $$$$(DTB_SIZE) \
 	  | append-kernel | pad-to $$$$(KERNEL_SIZE) | append-ubi
 endef