ANDROID: sched: avoid placing RT threads on cores handling softirqs

In certain audio use cases, scheduling RT threads on cores that are
handling softirqs can lead to glitches. Prevent this behavior.

Bug: 31501544
Bug: 168521633
Change-Id: I99dd7aaa12c11270b28dbabea484bcc8fb8ba0c1
Signed-off-by: John Dias <joaodias@google.com>
[elavila: Port to mainline, amend commit text]
Signed-off-by: J. Avila <elavila@google.com>