oc-mr1-dev is OC-MR1, don't allow building beyond it

Bug: 63544673
Test: Can't lunch marlin-userdebug-PPR1
$ lunch marlin-userdebug-PPR1
build/core/version_defaults.mk:55: Invalid TARGET_PLATFORM_VERSION 'PPR1', must be one of
build/core/version_defaults.mk:56: *** OPM1.  Stop.

Change-Id: I116b0cebb353600277876eabccf41e7dda736151
Merged-In: I2d9019af8c4e24e34c743be85d4e0ff224de9d17