build.prop for ODM partition is under ./etc subdir

build.prop for the ODM partition should be placed under ./etc directory
to support GSI. For detailed reasons, see
I0733c277baa67c549bb45599abb70aba13fbdbcf

The path was changed to /odm/build.prop during the recent refactoring
around build.prop filems and this change fixes the mistake.

Bug: 132128501

Test: check if odm/etc/build.prop is created
Change-Id: Icc2c564250aa08786f32294a839cc81e86b7d368
diff --git a/core/sysprop.mk b/core/sysprop.mk
index 0cee81c..fdf92b7 100644
--- a/core/sysprop.mk
+++ b/core/sysprop.mk
@@ -361,7 +361,7 @@
     $(empty)))
 
 # ----------------------------------------------------------------
-# odm/build.prop
+# odm/etc/build.prop
 #
 _prop_files_ := $(if $(TARGET_ODM_PROP),\
     $(TARGET_ODM_PROP),\
@@ -373,7 +373,9 @@
     ADDITIONAL_ODM_PROPERTIES \
     PRODUCT_ODM_PROPERTIES
 
-INSTALLED_ODM_BUILD_PROP_TARGET := $(TARGET_OUT_ODM)/build.prop
+# Note the 'etc' sub directory. For the reason, see
+# I0733c277baa67c549bb45599abb70aba13fbdbcf
+INSTALLED_ODM_BUILD_PROP_TARGET := $(TARGET_OUT_ODM)/etc/build.prop
 $(eval $(call build-properties,\
     odm,\
     $(INSTALLED_ODM_BUILD_PROP_TARGET),\