Revert "Rename init_boot properties to ro.init_boot.*"

This reverts commit 411fac84d67970b0c06c67c7ab41224166564e3b.

Reason for revert: b/226318737

Change-Id: Ie1cf0e79b3ac11b91e031a479898a54856020500
diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index 1c29273..9feb8af 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -498,9 +498,9 @@
   def GetPartitionBuildProp(self, prop, partition):
     """Returns the inquired build property for the provided partition."""
 
-    # Boot image uses ro.[product.]bootimage instead of boot.
+    # Boot image and init_boot image uses ro.[product.]bootimage instead of boot.
     # This comes from the generic ramdisk
-    prop_partition = "bootimage" if partition == "boot" else partition
+    prop_partition = "bootimage" if partition == "boot" or partition == "init_boot" else partition
 
     # If provided a partition for this property, only look within that
     # partition's build.prop.