libmedia: restrict nuplayer from using track offload

NuPlayer sets _NONE flags in the default path, this
leads to nuplayer using audio track offload, even
though the decision was to use deep buffer.
Restrict this behavior only to platforms
that have track offload enabled

Change-Id: I6191362850014f14c0e10da5bd30be86527fad34
CRs-Fixed: 833895