netd: Remove remaining usages of select() in netd.

Bug: 79838856
Test: as follows:
    - m ndc
    - copy ndc binary to device
    - adb shell ndc monitor
    - cause some netd activity by re-associating to wifi
Change-Id: I7c641114d16a6b2b95dedc9edfaf8964f5bb9412
4 files changed