Fixing protoOutParams concatenation.

ParseGeneratorParameter delimits based on commas, not colons:
external/protobuf/src/google/protobuf/compiler/code_generator.cc

Bug: 72570104
Test: flash device with new build
Change-Id: I00042782a718d288ca6b0cb78f856d0fb223a926
(cherry picked from commit fb5b31ce)