Revert "Revert "ANDROID: softirq: defer softirq processing to ksoftirqd if CPU is busy with RT""

This reverts commit 28768780, as the
merge conflicts have been resolved.

Bug: 168521633
Change-Id: I9828d641e92e40a798e899b60aba83dbc59675bb
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
[satyap@codeaurora.org: trivial merge conflict resolution.]
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>
[elavila: Port to mainline, squash with bugfix]
Signed-off-by: J. Avila <elavila@google.com>
[ashayj@codeaurora.org: trivial merge conflict resolution.]
Signed-off-by: Ashay Jaiswal <ashayj@codeaurora.org>
Signed-off-by: Shaleen Agrawal <shalagra@codeaurora.org>