drivers: qcom: sdx_ext_ipc: keep wakeup irq always on

When suspend is in progress on local processor, if
remote processor toggles GPIO to indicate a resume
event to local processor, this event may get lost.
This commit addresses this situation.

1. Add IRQF_NO_SUSPEND flag so that wakeup_irq is
not disabled during suspend on local processor.

2. Install primary handler that inform pm core
that a system wakeup event has happened. The pm
core can then abort a suspend in progress.

Change-Id: I8d84f15a118c4630bde7b9db35ffadddeb937cb9
Signed-off-by: Pavankumar Vijapur <pvijapur@codeaurora.org>
Signed-off-by: Yogesh Lal <ylal@codeaurora.org>