[Add kernel_in_ubi feature to separate image format]

[Description]
Add kernel_in_ubi feature to separate image format
1. add kernel in ubi feature
2. mtk.nand and factory/sysupgrade image will gen after do_image_complete

[Release-log]

diff --git a/conf/machine/filogic830.conf b/conf/machine/filogic830.conf
index 468f92e..4410b6d 100644
--- a/conf/machine/filogic830.conf
+++ b/conf/machine/filogic830.conf
@@ -28,6 +28,7 @@
 
 DISTRO_FEATURES_append = " meshwifi"
 DISTRO_FEATURES_append = " ipv6"
+#DISTRO_FEATURES_append = " kernel_in_ubi"
 
 # kernel 5.4 gold linker 'arm-rdk-linux-gnueabi-ld' not supported
 #DISTRO_FEATURES_append = " referencepltfm "