ramips: allow JCG_MAXSIZE in kiB in Build/jcg-header

This allows JCG_MAXSIZE to be specified in kilobytes. This makes
this value more consistent and easier comparable with other size
variables.

This also changes the only occurence of the variable, for Cudy WR1000.

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

target/linux/ramips/image/Makefile

@@ -48,7 +48,9 @@ define Device/seama
 endef
 
 define Build/jcg-header
-	$(STAGING_DIR_HOST)/bin/jcgimage -v $(1) $(if $(JCG_MAXSIZE), -m $(JCG_MAXSIZE),) -u $@ -o $@.new
+	$(STAGING_DIR_HOST)/bin/jcgimage -v $(1) \
+		$(if $(JCG_MAXSIZE), -m $$(($(subst k, * 1024,$(JCG_MAXSIZE)))),) \
+		-u $@ -o $@.new
 	mv $@.new $@
 endef
 

target/linux/ramips/image/mt76x8.mk

@@ -37,7 +37,7 @@ define Device/cudy_wr1000
   IMAGES += factory.bin
   IMAGE/factory.bin := \
         $$(sysupgrade_bin) | check-size $$$$(IMAGE_SIZE) | jcg-header 92.122
-  JCG_MAXSIZE := 8060928
+  JCG_MAXSIZE := 7872k
   DEVICE_VENDOR := Cudy
   DEVICE_MODEL := WR1000
   DEVICE_PACKAGES := kmod-mt76x2