ath79: image: don't depend on other COMPILE targets

A device COMPILE target should not depend on another COMPILE.
Otherwise race condition may happen.
The loader is very small. Compiling it twice shouldn't
have a huge impact.
Signed-off-by: NAlexander Couzens <lynxis@fe80.eu>
(cherry picked from commit 17c6fb10)

target/linux/ath79/image/Makefile

@@ -83,7 +83,7 @@ define Device/loader-okli-uimage
   LOADER_TYPE := bin
   COMPILE := loader-$(1).bin loader-$(1).uImage
   COMPILE/loader-$(1).bin := loader-okli-compile
-  COMPILE/loader-$(1).uImage := append-loader-okli $(1) | pad-to 64k | \
+  COMPILE/loader-$(1).uImage := loader-okli-compile | pad-to 64k | \
 	lzma | uImage lzma
 endef