Revert "DO NOT MERGE: P is now REL"

This reverts commit 2325d05510c5883ec182945c7ca4547fea5bf1ab.

Reason for revert: Broke -plus-aosp builds.  Reverting there to fix.

Change-Id: I625092da1df78ac76590ab27b01ed6f506e5e237
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index 7f55172..0f31163 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -86,7 +86,7 @@
 
 # These are the current development codenames, if the build is not a final
 # release build.  If this is a final release build, it is simply "REL".
-PLATFORM_VERSION_CODENAME.PPR1 := REL
+PLATFORM_VERSION_CODENAME.PPR1 := P
 
 ifndef PLATFORM_VERSION
   PLATFORM_VERSION := $(PLATFORM_VERSION.$(TARGET_PLATFORM_VERSION))