codec2: fix build by assigning absolute namespace path ::base

ag/4009937 produces compile error after C2VDAComponent includes
"v4l2/C2VDABQBlockPool.h", there is "namespace android::base" which misleads
compiler to find the correct "namespace base" in libchrome.

To solve this, change to use absolute namespace "::base".

Bug: 79239042
Test: build image
Change-Id: I74658afa1797d5a48dbb1844628a57f3f533c25e
1 file changed