msm: msi: set enable_irq_wake for PCIe MSI IRQ

To guarantee PCIe client MSI can wake up APPS while its in LPM,
call enable_irq_wake on the parent MSI, PCIe MSI IRQ. Doing so
will make sure these IRQs are not disabled as part of APPS system
suspend.

Change-Id: Ifdb74068a26eca7028667310d62df8b974e58927
Signed-off-by: Tony Truong <truong@codeaurora.org>