Revert "ANDROID: sched: avoid migrating when softint on tgt cpu should be short"

This reverts commit 8d19443b 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: 31752786
Bug: 168521633
Cc: John Dias <joaodias@google.com>
Cc: J. Avila <elavila@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I6875407b586f505c2045e4cf40682831b4fceac1