ANDROID: sched/rt: Add support for rt sync wakeups

Some rt tasks undergo sync wakeup. Currently, these tasks will be placed
on other, often sleeping or otherwise idle CPUs, which can lead to
unnecessary power hits. Support rt sync wakeups, but only enable
rt sync for SMP targets.

Bug: 157906395
Bug: 323845182
Old-Change-Id: I48864d0847bbe4f7813c842032880ad3f3b8b06b
Change-Id: Ia22b2077969c023e6b0d40861626d55420f657ad
Signed-off-by: J. Avila <elavila@google.com>
[quic_dickey@quicinc.com: Port to mainline]
Signed-off-by: Stephen Dickey <quic_dickey@quicinc.com>
[quic_snimmala@quicinc.com: Fixed conflicts in core.c]
Signed-off-by: Sai Harshini Nimmala <quic_snimmala@quicinc.com>
[jstultz: Cherry-picked forward]
Signed-off-by: John Stultz <jstultz@google.com>