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

This reverts commit 0578248b as the
softirq code is rewritten in 5.11-rc1 and massive merge conflicts are
happening.

If this change is still needed, please work with upstream to get the
patches accepted so they can then come into this tree automatically.

Bug: 168521633
Cc: Pavankumar Kondeti <pkondeti@codeaurora.org>
Cc: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>
Cc: J. Avila <elavila@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I421cc2ca29b635d7ac39d52aa486e20cbdd8ca45