image: allow devices to override the -E 5 ubinize option

Signed-off-by: Felix Fietkau <nbd@nbd.name>

include/image.mk

@@ -327,6 +327,7 @@ define Device/Init
   BLOCKSIZE :=
   PAGESIZE :=
   SUBPAGESIZE :=
+  UBINIZE_OPTS := -E 5
 
   FILESYSTEMS := $(TARGET_FILESYSTEMS)
 endef
@@ -334,7 +335,8 @@ endef
 DEFAULT_DEVICE_VARS := \
   DEVICE_NAME KERNEL KERNEL_INITRAMFS KERNEL_INITRAMFS_IMAGE \
   UBOOTENV_IN_UBI KERNEL_IN_UBI \
-  BLOCKSIZE PAGESIZE SUBPAGESIZE
+  BLOCKSIZE PAGESIZE SUBPAGESIZE \
+  UBINIZE_OPTS
 
 define Device/ExportVar
   $(1) : $(2):=$$($(2))