PM / devfreq: bimc-bwmon: Update irq handling in suspend/resume

Change the sequence of registering and freeing the interrupt
handler in suspend/resume. Freeirq needs a guarantee that the
IRQ can't come anymore before we call it. So, we disable the IRQ
before calling freeirq.And register the handler before enabling
the irq to avoid the interrupt getting unhandled.

Change-Id: I3945202d049e16f64a16e456f914f7602b763c89
Signed-off-by: Hanumath Prasad <hpprasad@codeaurora.org>