Allow devices to specify certain ro. props via TARGET_UNIFIED_DEVICE

This modifies buildinfo.sh to not set model, name, description, and
fingerprint in build.prop. These can then be set via custom init
lib.
This also fixes ota_from_target_files to function without these
props being preset.

Change-Id: I945b2c38e60b207d2d0f82b34f4f230ac21b0657
diff --git a/tools/buildinfo.sh b/tools/buildinfo.sh
index 310d478..a5d0e21 100755
--- a/tools/buildinfo.sh
+++ b/tools/buildinfo.sh
@@ -20,10 +20,8 @@
 echo "ro.build.host=`hostname`"
 echo "ro.build.tags=$BUILD_VERSION_TAGS"
 echo "ro.build.flavor=$TARGET_BUILD_FLAVOR"
-echo "ro.product.model=$PRODUCT_MODEL"
 echo "ro.product.brand=$PRODUCT_BRAND"
 echo "ro.product.name=$PRODUCT_NAME"
-echo "ro.product.device=$TARGET_DEVICE"
 echo "ro.product.board=$TARGET_BOOTLOADER_BOARD_NAME"
 
 # These values are deprecated, use "ro.product.cpu.abilist"
@@ -48,11 +46,15 @@
 echo "# ro.build.product is obsolete; use ro.product.device"
 echo "ro.build.product=$TARGET_DEVICE"
 
-echo "# Do not try to parse description, fingerprint, or thumbprint"
-echo "ro.build.description=$PRIVATE_BUILD_DESC"
-echo "ro.build.fingerprint=$BUILD_FINGERPRINT"
-if [ -n "$BUILD_THUMBPRINT" ] ; then
-  echo "ro.build.thumbprint=$BUILD_THUMBPRINT"
+if [ "$TARGET_UNIFIED_DEVICE" == "" ] ; then
+  echo "ro.product.model=$PRODUCT_MODEL"
+  echo "ro.product.device=$TARGET_DEVICE"
+  echo "# Do not try to parse description, fingerprint, or thumbprint"
+  echo "ro.build.description=$PRIVATE_BUILD_DESC"
+  echo "ro.build.fingerprint=$BUILD_FINGERPRINT"
+  if [ -n "$BUILD_THUMBPRINT" ] ; then
+    echo "ro.build.thumbprint=$BUILD_THUMBPRINT"
+  fi
 fi
 echo "ro.build.characteristics=$TARGET_AAPT_CHARACTERISTICS"