cpufreq: schedutil: Queue sugov irq work on policy online cpu

Got never update frequency if scheduled the irq
work on an offlined cpu and it will always pending.
Queue sugov irq work on any online cpu if current
cpu is offline.

Change-Id: I33fc691917b5866488b6aeb11ed902a2753130b2
Signed-off-by: Maria Yu <aiquny@codeaurora.org>
[clingutla@codeaurora.org: Moved 'walt_irq_work_queue' to 'sched.h'
 for multiple callers]
Signed-off-by: Lingutla Chandrasekhar <clingutla@codeaurora.org>