sched: avoid scheduling RT threads on cores currently handling softirqs

Bug: 31501544
Change-Id: I99dd7aaa12c11270b28dbabea484bcc8fb8ba0c1
Git-commit: 080ea011fd9f47315e1fc53185872ef813b59d00
Git-repo: https://android.googlesource.com/kernel/msm


[pkondeti@codeaurora.org: resolved minor merge conflicts and fixed
checkpatch warnings]
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
[satyap@codeaurora.org: resolve trivial merge conflicts]
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>