Refactor the InetSocketAddress in MulticastPacketReader to use port zero

Refactor the InetSocketAddress in MulticastPacketReader to use port zero
because this value is only a placeholder that will be overwritten
when recvfrom() is called.

Test: atest CtsNetTestCases FrameworksNetTests
Bug: 279691736
(cherry picked from https://android-review.googlesource.com/q/commit:58d79613bf25f4de282b891bd3e314a191adc1c4)
Merged-In: Idb9d8a96e1f10eb2ede972125430c84af6b539d9
Change-Id: Idb9d8a96e1f10eb2ede972125430c84af6b539d9
2 files changed