media.c2 : Change waitable object to be based on single fd

Currently watiable object is based on two file descriptors created by
eventfd(). Change waitable object to be based on signle fd created by
pipe2().

Bug: 254050314
Test: m
Change-Id: I6771868a93c9bfb767c904d89a3a523e370b3e7e
2 files changed