Rename init_boot properties to ro.init_boot.*

Right now they're named ro.bootimage.* which is really confusing.
Change it so that if generic ramdisk is in boot.img, then name the
properties as ro.bootimage.*, otherwise if generic ramdisk is in
init_boot.img, then name the prop as ro.init_boot.*.

Bug: 211823573
Test: m dist
Change-Id: Icff3c7be04b9a3c6490fbf49ba4f05565b029890
diff --git a/core/sysprop.mk b/core/sysprop.mk
index 43b8953..63574d0 100644
--- a/core/sysprop.mk
+++ b/core/sysprop.mk
@@ -501,10 +501,11 @@
 # ramdisk/boot/etc/build.prop
 #
 
+RAMDISK_PARTITION_NAME := $(if $(BUILDING_INIT_BOOT_IMAGE),init_boot,bootimage)
 RAMDISK_BUILD_PROP_REL_PATH := system/etc/ramdisk/build.prop
 INSTALLED_RAMDISK_BUILD_PROP_TARGET := $(TARGET_RAMDISK_OUT)/$(RAMDISK_BUILD_PROP_REL_PATH)
 $(eval $(call build-properties,\
-    bootimage,\
+    $(RAMDISK_PARTITION_NAME),\
     $(INSTALLED_RAMDISK_BUILD_PROP_TARGET),\
     $(empty),\
     $(empty),\