msm: pil: Proxy unvote after pil_shutdown() when using IRQs

Subsystems might use an IRQ for removal of proxy votes via the
power/clock ready interrupt. So, if a peripheral shutdown is triggered
before the power/clock ready interrupt is received, remove the proxy
votes and bypass the unvoting in the power/clock ready interrupt handler.
Conversely, if the power/clock interrupt is received before shutdown is
triggered, bypass the unvoting during pil shutdown.

Also, remove the hack to proxy unvote directly from the pil-q6v5-mss
driver.

Change-Id: I254ab5a1595ceb27a2cfcac99c4c1d2f2443b7c7
Signed-off-by: Seemanta Dutta <seemanta@codeaurora.org>