msm: pil-q6v5-mss: Perform proxy voting/unvoting at mba bootup

Currently, both mba and q6 devices perform voting and unvoting during
bootup via pil. This is done because earlier the clock ready interrupt was
not provided by the modem booting up. But now that we have the clock ready
interrupt being sent by the modem, we can make the proxy votes for the PBL
while booting up. Later when the modem has finished booting up it would
send the clock ready interrupt and at that time we would remove the proxy
votes made for the PBL. So remove the PBL proxy votes after receiving the
clock ready interrupt from the modem.

Also, having IRQF_SHARED in the proxy unvote IRQ registration is
unnecessary because the the power/clock ready interrupt is not shared
among subsystems. So remove that as well.

Change-Id: Ie6ec27f6842c42c4240a9f09f8f49a190ab3c2f9
Signed-off-by: Seemanta Dutta <seemanta@codeaurora.org>